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More than half of the introduction for incandescent light bulbs is talking about switching from them to CFLs. This seems completely bizzare and out-of-place. 69.141.68.106 01:21, 23 May 2007 (UTC)
...not spontaneous emitters. The following:
"As the electrons that travel through the filament bump into the atoms, some of the electrons in the atom may become excited. This means they temporarily boost its energy level and raise to higher orbit. When they fall back, energy is released as photons, a photon being the particle form of light."
is true, but the vast majority of the light comes from blackbody radiation, which isn't even mentioned. I guess this is what happens when you copy from howstuffworks.com... 168.230.48.248 03:25, 5 July 2006 (UTC) (Andrew)
I agree - as a physics graduate, incandescent bulb spectrums are NOT shaped primarily by electron transitions in **atomic** tungsten. This is somewhat misleading and is wrong if you're trying to explain how an incandescent bulb gets its light spectrum. Black body radiation accounts for most of the spectrum's (continuous) shape and is also the reason why incandescent bulbs tend to look very natural to the human eye compared to other types of lighting - the sun's light is mostly shaped a lot by black body radiation too! Though electron transitions facilitate blackbody radiation, it's not the atomic structure of tungsten that provides the spectrum. I've reworded this. Physicists please check that I've given a correct explanation. 18.250.0.177 15:02, 8 November 2006 (UTC)
In revision 139201 an anonymous user inserted a large block of slightly modified text from external websites ( [1], [2], [3], [4]). The contributor that did this seems to have copied passsages of text from several different wesites and pasted them together with minor to moderate rewording of some sentences. This is not covered under fair use. Fortunately, others have since copyedited the text and have obscured much of the obvious parentage. More is needed however. Please keep this in mind while editing. -- mav
Hey, I'm all kinds of new here, but is there *any* substantiation to this "modern lightbulbs filled with inert gas" buisness? I know we have neon lights, but the article seems to imply that modern incandescent bulbs are not evacuated, but any good (although not safe, and not reccomended) smashing of lightbulbs proves that they are at least nearly evacuated. -j
Be careful using a shatter test on 'neon' lamps. If you get a cut it can take a long time to heal due to the chemicals used to coat the inside of the glass. At least so I have heard.
Plus, drops of liquid mercury and other nasty chemicals in fluorescent lamps likely turn to minute droplets and go airborne when the tubes are smashed.
The whole paragraph about Davy's work could stand to be rewritten, preferably by someone who has consulted contemporary sources.
Edison 21:22, 20 June 2007 (UTC)
The article Light bulb says in section History of the light bulb
I assume (not much of chemist, i) that oxidation of Pt is unlikely, and that this misinterprets Lights by Edward Willett, or something similar, which refers to
I say "oxidation ... unlikely" in the belief that Davy chose Pt bcz that (and maybe Au) were the only things he could find that didn't oxidize when incandescant (and maybe bcz Au melts a lot earlier).
Here are some #s from WP:
Parameter ---------- W ----- Pt
Melting point --- 3695 K 2041.4 K
Boiling point --- 5828 K 4098 K
ρ-1 (106/m ohm) -- 18.9 09.66 (or should i be suspicious of the leading zero?)
At. wt. (amu) --- 183.84 195.078
What i understand to be the main failure mechanism in ductile-tungsten filaments is the positive feedback at the hottest points, of
culminating in local melting across the whole cross-section, of enuf length that sag (or just instability?) lets the liquid portion flow away from its center. (Haven't noticed if that's in the article; it should be IMO.)
IMO, the presence or absence of air doesn't make a lot of difference in that kind of failure, bcz even if convection is more efficient for the first few inches than radiation alone, incandescence is required, and the operating temperatures are going to be essentially the same.
With Pt in the same geometry such failure just happens sooner; i imagine much sooner: i base that on the principle that chemical reaction rates go up very rapidly with temperature bcz they are controlled by the population in excess of the activation energy, which increases much faster than mean energy, and on my belief that thermal migration should similarly limited by an activation energy representing a surface atom breaking all but two (or if not, all but one) of its bonds, so it can swing to its next position.
The higher conductance of W (which surprises me, but whadda i know) does mean the Pt filament has twice the cross-section area for the same length, voltage and current, but that may not be what determines the geometry: with modern W, it may be economical for filaments to be made thicker and longer (for ruggedness and reduced thermal-migration failure, but with Pt the cost of filament material has to limit the feasible increase of dimensions. So i think the lower conductance is completely swamped by the melting point and perhaps dimension issues, and i am convinced the same non-oxidative failure mechanism can explain Davy's results. -- Jerzy '03 Dec 15
Thx! On reflection i agree. I may have been searching for my keys under the street lamp, esp since i despair of having any hope of estimating sublimation rates, either relative between materials or relative to the solid-state thermal surface migration -- other than to note that activation energy for sublimation has to be higher than for surface diffusion. Maybe i should have taken another thermo course or four.
I think sublimation can also participate in the feedback loop, but at least initially it promotes a graceful degradation, with the bulb getting cooler (and dimmer) as the filament thins and delivered power drops.
(My first thot on reading the sublimation contrib was "Ah, then the bulb maintains a vapor pressure of the filament material, and makes a difference other than via restricting convection to a remote heat-flow mechanism." No, fool, the bulb just makes it obvious that sublimation is a second thermal-migration mechanism that you didn't even consider: thermal migration via gas phase to the sub-incancesent bulb instead of via solid phase within the filament. 'Scuse me, gotta go off and cry somewhere.) -- Jerzy 19:41, 2003 Dec 16 (UTC)
Don't be too hard on yourself, Jerzy. You were right to dispute the "oxidized" claim (which I just changed).
Looking into this further, I think sublimation may be a less graceful degradation mechanism than you say, but I'm not sure. For analytical purposes, I imagined a filament divided into 100 segments in series. For a 240 V 100 W bulb (common here in Britain), I calculate the filament resistance when hot to be nominally 576 R. In my scheme that's 100 5.76 R segments in series. If, due to evaporation, one segment doubles in resistance to 11.52 R, then the total filament resistance will increase by 1% to 581.76 R. With the same supply voltage, the power will drop by nearly 1% to 99.01 W. As you said, this will cool the bulb and help to slow down the evaporation. On the other hand, think what happens to the thinned segment. The current through the filament has now dropped by 1% (from 0.4167 A to 0.4125 A), but the resistance of the unfortunate segment has doubled, so the power in that one segment has now increased by 96% (from 1 W to 1.9606 W), making it evaporate much faster! It seems that the increase in local power dissipation will strongly dominate the slight decrease in global power dissipation, causing a runaway failure, but I haven't proved that this is true for all cases.
If you have been, thanks for reading this far! -- Heron
A big issue i keep coming back to, tho, is that we'd like to find phenomena that work when the non-uniformities are infinitesimal. I think your example points out the fact that power goes up faster than segment resistance, because P = VR2, which enhances the feedback, at least once the uniformities get large. But what i'm starting to worry about is that unless we're talking about irregularities that are there from the factory machining, they are likely to be swamped by the thermal noise. IMO there are some things that work against the feedback: i think infinitesimal surface roughnesses are subject to negative feedback: atoms at convex surface points are bound to fewer atoms and therefore (i think) less strongly bound; atoms at concave surface points by the same token more strongly bound. We therefore expect the background surface diffusion (the component not driven by temp differences) to favor moving atoms from convexities to concavities, and smooth out the surface. Gets more complicated as we examine more closely, i fear.
It sounds, tho, like you know no more than i abt how hard it is to oxidize Pt at those temps, & i fear our alternate failure mechanism (instead of fairly uniform erosion (or resistance increase, on the assumption that the oxide is non-conducting but non-volatile), by oxidation) is irrelevant - i.e., if there's nothing wrong with the previous editor's oxidation hypothesis!
What i haven't done is finished searching the web for statements that Davy's Pt failed by oxidation; i've been treating the suspicious text like a smoking gun, but there may be a more credible source out there that says "oxidation" explicitly.
Interesting, nonetheless. [smile] -- Jerzy 03:28, 2003 Dec 17 (UTC)
You are right to say that I don't understand the chemistry of what's happening. I will leave that to someone else.
"The Invention of the Incandescent Lamp" by Globusz Publishing, among other web pages, points out (in somewhat convoluted English) that the temperature at which platinum glows is very close to its melting point, which is what makes it so unreliable. I think this is the (disappointingly simple) answer. -- Heron
I hope you will not mind if I throw my two cents in.
The failure modes of incandescent lights has interested me too. I think evaporation is an important failure mode, and you can confirm this by noting that high intensity bulbs build up a dark layer on tungsten (or whatever) on the inside of the bulb as they age. The halogen cycle helps slow down this loss. The bulb temperature must be very high though for this trick to work. This is why quartz glass must be used. Halogen lamps intended for projection use are rated for 50 hour life and are specified to operate at about 50C below the melting temperature of tungsten. The melting temperature of tungsten, I believe, is closely related to, and limits, the quoted "color temperature" of tungsten light. I believe that lamp lifetime varies with the sixth power (I forget, but the effect is big) of operating voltage, and I could look up the empirical derating formula if anyone cared.
What I really wanted to offer, though, is another observation. I believe that it is common for lamps to fail at the moment they are turned on. I have noticed that when incandescent lamps are dimmed very low using a phase control dimmer that they emit a noticable sound. I believe that tungsten lamp electrical loads draw a nominal 10x current surge when the load is first turned on, that is, the rule of thumb for sizing switch contacts, etc. is to expect this much surge. I believe this is due to the cold filament having a much lower electrical resistance initially. Careful examination of the phase control circuit waveform shows that there is an enormous, short duration current spike on each half cycle as the partially cooled filament is connected to a relatively high voltage, instead of the normal smooth sinusoidal voltage buildup. I believe that some of the corresponding noise may be from thermal distortion as the filament heats rapidly. However, I suspect, that some of the noise may be due to forces created by the rapidly changing, 10x magnetic field around the (usually) coiled filament, due to the current surge, acting on the conducor. I think this magnetic effect may also account for the tendency of the bulb to fail as it is turned on, by adding one more stress to the cold and weakened metal.
Quoth the article:
This is quite different from the Davy lamp described in the linked article (basically, a safety mechanism for an open-flame "lamp" that allows it to be used in mines where flammable gasses may be present). Is the description of the lamp here wrong, or is it not the same lamp that came to be known as the Davy lamp, or is the other article at fault, or what? The other article _feels_ more reliable to me than this one, but that's a highly subjective assessment made without any real background in the subject matter, and in any case even if the Davy lamp article is assumed correct it is not obvious how to rectify this (incandescent light bulb) article. The section probably ought to be flagged for reworking, but I'm not sure which tag best applies. For now I have used the "Not verified" flag; feel free to replace it with a more appropriate one if such exists.
I was browsing around and came across a guy's rant [11] which also includes a lot of great info on light bulbs. I'm not sure if it's proper to include as an external link, though.
I see that light bulb redirects to incandescent light bulb. I think it should go the other way around -- this article discusses flourescent, carbon arc, and other non-incandescent lights. So I think this article should be titled simply "light bulb". Should we simply move the article, or would it be better to split it up into a general "light bulb" article and a specific "incandescent" article ? -- DavidCary 03:08, 10 Sep 2004 (UTC)
Please note that most of the articles use the noun "lamp" rather than light. So if you're going to move this, it would probably be better to move it to "Incandescent lamp" rather than anything named "... light".
Atlant 13:01, 17 Dec 2004 (UTC)
Now I'm confused. My recollection was that MES was minuature Edison screw, the standard torch (flashlight) bulb, and that LES was liliputian Edison screw, an even smaller bulb used in torches and as indicator lamps (in the days before LEDs). But the article uses MES to mean medium Edison screw, the standard light fitting. I always thought this was just ES. Also pretty sure I've come across things described as SES (small Edison screw) -- perhaps this is equivalent to the candelabra fitting mentioned? Or perhaps I'm just confused Roy Badami 18:33, 28 Mar 2005 (UTC)
Article says "the E stands for Edison, who created the screw-base lamp, and the number is screw cap diameter in eighths of an inch in the U.S." This does not compute, as that would mean an E26 is 3.25 inches in diameter (8.3cm). Thirty-seconds of an inch would make more sense. I'm going to take out the "eighths of an inch" until a better explanation is provided. ---Ransom (-- 208.25.0.2 16:53, 9 May 2006 (UTC))
It would be useful to include a bit about what Type A, Type B, etc. bulbs are. The article only discusses the screw fitting, but many manufacturers refer to Type A bulbs...
LEDs are much more efficient than the stated 20lm/w. see: http://www.lrc.rpi.edu/resources/news/pressReleases/spemethod.asp
Not true - at least, not true for white LEDs. Depite the hype that pervades the industry about the future potential efficacy of LEDs used for lighting, the actual specs of real-life LED products for lighting applications is in the range of 20 - 25 lumens per watt. This is less than one third of the efficacy of compact fluorescent bulbs. You can verify this by checking the specifications of products of leading high-brightness LEDs from manufacturers such as Lumileds:
http://www.lumileds.com/pdfs/DS45.PDF
Colored LEDs may be quoted with higher efficacies because green and adjacent colors sit at the peak of sensitivity of the eye. However, this is no indicator of their usefulness for general purpose illumination. You have to be looking at the white-light specs in order to do an apples-for-apples comparison with other white light sources such as compact fluorescent.
Well, my grandmother in Pennsylvania calls them light globes, so the above claim is too strong. I always figured it was a largely obsolete term from her youth, that has fallen out of favor in the U.S. Anyone else know of "light globe" being used outside of Australia and S.A.? -- Coneslayer 15:09, 2005 July 28 (UTC)
Maybe someone can offer some insight here. The spectra that I recently uploaded of a (unfiltered, clear) flashlight bulb [12] appears to have a peak emission of around 630 nm. However this [13] says the filament should therefore have a temperature of ~4600K which is clearly impossible.... Does the glowing filament deviate from a blackbody that severly as to make an approxamation like this impossible? What happened?-- Deglr6328 06:39, 5 September 2005 (UTC)
There seem to be several sections in this article that independently make comparisons between Incandescent bulbs and various other types of lighting. eg. Comparison of electricity cost compares with the cost of compact fluorescent, Efficiency compares with a bunch of other types, Heat makes comparisons with compact fluorescent lights, and so on. I was wondering if it'd be beneficial to have a separate article to consolidate comparisons between lighting types... or maybe it could be part of the light bulb article (mentioned above), or the lighting article.
I've worked on the light pollution article a lot recently. I started drawing a table comparing different types of lighting, but then began wondering such a list really belonged there. For one thing, it seems to be duplicating a lot of lighting information available in many of the different lighting articles, just as the comparisons in this article probably duplicate the same information elsewhere. Does anyone have any thoughts about this? Izogi 07:34, 6 September 2005 (UTC)
I wondered if the tungsten use was an alloy or pure (mostly) tungsten? Anyone know?
Efficacy might be a correct term, but to me it seems less specific than energy efficiency, and the linked efficacy article doesn't (currently) seem to or address the idea at all. On the contrary, it's very weighted towards psychological meanings, with small cameos for medicine and politics. It isn't anywhere near as helpful as the energy efficiency article was. The efficacy article could almost be a disambiguation page, or have some redirect text at the top to point people at energy efficiency if they want something about energy. Anyway, I'm not quite sure what the best approach is here. I'd quite like to point the links back to energy efficiency, because it seems to be more specific and it is a more widely recognised term, in my opinion. In the interests of avoiding an edit war, though, does anyone have any strong opinions on this? Izogi 22:24, 9 September 2005 (UTC)
But what was incorrect about energy efficiency in the first place? I just think it's clearer, not to mention more specific. Izogi 08:15, 10 September 2005 (UTC)
Fine with me. Izogi 21:37, 10 September 2005 (UTC)
The heading "efficiency" in the table is incorrect and misleading. The percentage figures in that table express the lumens delivered by one radiated watt as a proportion of the theoretical maximum of 681. They depend only on the shape of the spectrum and they do not account for any "efficiency" concept whatsoever. To use the term "efficiency" in this context is misleading - well, actually not misleading - just plain wrong. Using the term "efficacy" is also wrong because that's a clearly defined term and this isn't it. I am not aware of any properly defined term that describes the figure shown in that column so I can't offer a solution - I only offer that "efficiency" is NOT the correct term.
When you go to "Incandescent light bulb" from the Search it gives you this: The invention of the light bulb is usually attributed to Amanda "Mugsy" Emms, who contributed to its development by producing a practical and viable electric lamp. However her invention was stolen by Thomas Edison who marketed the device successfully. Alexander Nikolayevich Lodygin developed an incandescent light bulb around the same time. Many others also had a hand in the development of a practical device for the production of electrically powered lighting.
But when you go to "Light Bulb" from the search it gives you this: The invention of the light bulb is usually attributed to Thomas Alva Edison, who contributed to its development by producing a practical and viable electric lamp, and marketed the device successfully. However, it is now believed that Heinrich Göbel built functional bulbs three decades earlier. Alexander Nikolayevich Lodygin developed an incandescent light bulb around the same time. Many others also had a hand in the development of a practical device for the production of electrically powered lighting.
I honestly don't know much about the lightbulb so I'm not going to correct it on a hunch (no matter how big), but I've never heard of the Amanda Emms version of the story. Also why is there two different pages that claim to redirect to the same place [Incandescent light bulb]? -- Taboo Tongue 20:13, 19 November 2005 (UTC)
It's my understanding that the Woodward and Evans light bulb did in fact work and that Thomas Edison thought that their approach was sufficiently promising to buy rights to their patents. I am not an expert in the field, however. My source is [16]. I would gladly defer to another who is more expert or who can provide a more authoritative source. On another note, what's the point of emphasizing that Woodward was not a "gentleman" (presumably a noble?) but "merely" a hotel operator. It may be true, but unless it's relevant to the history of the develpoment of the light bulb, I recommend that that fact be removed.-- Nowa 00:15, 21 December 2005 (UTC)
Thomas Edison has been nominated on WP:IDRIVE. Vote for this article and help improve it to featured status. -- Fenice 14:02, 26 December 2005 (UTC)
There are too many links, especially in the intro paragraphs, and some ("archaically"?) are not really relevant to the context. See Wikipedia's style info on this. I'm taking out links to some plain English words and irrelevent words. Benhoyt 03:10, 6 March 2006 (UTC)
I have changed the comparision of electricity cost to reflect more accurately the lumen output of a CFL. 13-15w CFL's output 800-900 lumens. In the range of a 60W lamp. See http://www.energyfederation.org/consumer/default.php/cPath/25_44_785 for an excellent sampling of CFL wattages and lumen outputs. The existing references also support ~14w CFL =~ 60w incandescent.
Now I'm no expert however I've been purchasing light bulbs for a while and I'm pretty sure the expected life time of a CFL one and an incandescent one is roughly the same, this is ofcourse greatly company dependent but if someone with the education could confirm and/or correct this?
Here in Norway (and Sweden?), the normal average lifetime for an incandescent lamp is 2500 hours. This is confirmed by independent tests (text in Norwegian), and a 40 W bulb brand with such lifetime was measured to emit 396 lumen on average, which seem to compare fairly to US bulbs. Osram, the manufacturer, makes lamps in their German factory rated at 1000 hours, and claims the longer life of the lamps made in Norway is due to special regulations! I wonder why the rest of the world doesn't copy our regulations... -- Kjetilho 00:40, 1 August 2006 (UTC)
The section on Power (as well as comments above) provides helpful information regarding long-life (130-volt) bulbs. However, it's not clear whether the chart in the Power section ("Comparison of efficacy by wattage") assumes these bulbs are operated at 120v or 130v. Hopefully the former, but in any case the assumption should be stated in the explanatory text next to the chart.
It makes no sense to define an efficiency percentage of a light bulb without a certain reference, since you cannot divide lumens by watts and get percents out. If you have a hypothetical light source that converts 1 W of electrical power into 1 W of light at 675 nm (typical wavelength for red laser pointers), then the energy efficiency of this light source is 100% (1 watt useful output per watt of input). However, according to the definition in the previous version (perfect monochromatic light source at 555.6 nm is 100%), the efficiency would be 2% and the other 98% are, as written in the beginning of the article, "wasted as heat". I don't think it is appropriate to call this "wasted as heat" just because the eye is a less sensitive to this wavelength than green 555.6 nm light. The appropriate way is to take the ratio useful output power (in watts) and total consumed power. One way to do is to take the part of the power which is emitted in the visible range, i.e. 420 to 700 nm (see luminosity function), in order to not count infrared and ultra-violet radiation. However, this would give too much weight to the almost-IR and almost-UV parts of the spectrum, and give an incandescent lamp a much higher efficiency than it deserves. Since the table is about efficiencies of sources for illumination, it has to evaluate light sources with a fairly broad spectrum. A light source that converts electricity into visible light in the range 420-700 nm cannot have an efficiency higher than 242 lm/W due to the fact that the eye needs other wavelength components than just 555.6 nm green in order to get the impression of a white light source. It is possible to calculate the optimum spectrum that will give you most lumens per watt while still give you daylight white rather than green. I don't know where exactly the 242 lm/W comes from (the original link pointed to an irrelevant page), but it seems quite reasonable judging from the shape of the luminosity curve, e.g. the number of lumens if you take one watt of flat-spectrum light in the range 420-700 nm.
So, to summarize: if the best possible spectrum that looks like white gives you 242 lm/W, then this should be considered the 100% efficiency point of an illumination device —Preceding unsigned comment added by hankwang ( talk • contribs)
I agree with hangwang's changes to the table. This brings it in line to what my college physics book says for the efficiency of incandescent and CFL lights. Perhaps the terminology needs to be clarified, but as far as the percentages go, they should remain as Hangwang has them. Perhaps the ideal monochromatic source should be removed. Why use pure (monochromatic) green light as a reference? TimL 15:39, 16 April 2006 (UTC)
Furthermore, the definition of Luminous efficiency is total lumimous flux over total radiant flux. So for both ideal white light source and monochromatic (555.4nm) source the correct percentage value would be 100%. I am now going to make this update. TimL 15:52, 16 April 2006 (UTC)
Leaving aside for the moment the issue of whether Hankwang's argument is correct, his reversion was not a good edit. If you look more closely, you'll see that I made a number of other changes, including carefully going through and fixing the references, which were messed up. The reason one of the references seemed irrelevant was because edits had caused the footnote numbering not to correspond to the correct notes. (This was a problem with the old footnote system. I changed the table over to the new footnote system.) The other problem is that, independent of what definition of efficiency Hankwang feels is appropriate, the definition of luminous efficiency used in his version of the table did not agree with the definition in the article text.
Now, as to the technical issue: What needs to go in the article is not what Hankwang things is best, but what is actually used. If someone can cite a reference that defines luminous efficiency, that would be justification for changing the table. Otherwise, I propose we keep what we had. I need to revert the edits to fix the references. If you want to change the numbers please edit the table instead of reverting it back to the version with the broken references. But, please provide a reference that justifies this change in the contents of the article rather than an argument about what seems best.
Even in terms of what seems best, though, the arguments above are incorrect. A monochromatic green source has higher luminous efficiency (and efficacy) than a white light source because if you compare two sources with the same power the monochromatic source will seem much brighter. You can see better by the source with the higher efficacy. To use Hankwang's example above, it's perfectly reasonable to say that the luminous efficiency of a 675 nm source is only a few percent. Anyone who has ever compared a 1 mW red laser spot to a 1 mW green laser spot knows this. Similarly, a monochromatic green source is brighter than a white light source of the same radiant flux. It's not great for illumination because it isn't white, but such sources are used. Ever seen a green LED nightlight? They are very energy efficient, and yet you can see quite well by them. In general, Hankwang's argument seems to not understand the purpose of the luminosity function or of luminous efficiency. Hankwang also seems to confuse "efficiency" and "luminous efficiency". These are not the same thing. Efficiency is about how much light is emitted, vs. how much is wasted as heat. Overall luminous efficiency is about how much of the energy consumed produces something that is useful for vision. Red light is less useful for vision than green light. White light is less useful for vision than green light too (in the sense that the latter is brighter than the former, for equivalent levels of radiant flux.) -- Srleffler 03:47, 17 April 2006 (UTC)
The comment for this edit should have read "100% is the maximum possible value for luminous efficiency." TimL 15:54, 16 April 2006 (UTC)
This lists glass halogen (2.3%), quartz halogen (3.5%) and tungsten-halogen (2.6%-3.6%). It seems like we have some overlap here in terminology, creating a longer table than necessary. (I also don't see how we need three rows for LED's but thats another story). Aren't glass halogen and quartz halogen two types of tungsten halogen lamps? Seems to me like we could do with just listing quartz halogen, or tungsten halogen.
About white LED's, since it is both a rapidly devloping and emerging technology, perhaps we could just have a footnote at the end of the table mentioning their possible efficiencies. TimL 04:01, 18 April 2006 (UTC)
Looking at the Klipstein reference for LED prototypes I found little evidence except for a very vague press release from Cree regarding 100 lm/w led. The press release refers to 'results', not any actual working prototype. I have created a new reference that talks about a prototype LED that procuces 80 lumens per watt, but only at extremly low currents. I also saw at the Klipstein page nothing about high vs. lo0w power LED's. So I removed the Low power line. In fact the chart on the new refernce I created suggests that LED's have a higher luminous efficiacy at low power. TimL 21:58, 19 April 2006 (UTC)
Edison 14:00, 2 April 2007 (UTC)
What does the following sentence mean?
Bamboo continued to be used until 1893, later enhanced by a cellulose coating, introduced around 1882 and produced until at least 1929.
Bamboo was obviously used without cellulose coating until 1882. From that year, it was coated in cellulose, but what happened between 1893 and 1929, when bamboo use had supposedly ceased, but cellulose coating had not? LX 06:05, 20 April 2006 (UTC)
Could be insert also the contribution to this invention by the italian scientist Alessandro Cruto? HI
-- 80.104.130.37 10:47, 8 May 2006 (UTC)
What is it about a fingerprint that destroys a quartz halogen lamp? According to http://www.its-90.com/al-sil.html, (last section, "PRECAUTIONS TO PREVENT DEVITRIFICATION OF QUARTZ ENVELOPES"), "Fused quartz is vitreous in nature but, like other glasses, can be stimulated to crystallise (devitrify) by external influences at high temperatures.... Sealed quartz cells can be used for thousands of hours without devitrification if precautions are taken to ensure that the outside surface is scrupulously clean before raising them to temperature. Any surface dirt, a water spot or a single fingerprint is a potential seed for devitrification." 208.42.18.222
I added a paragraph to this section, which I'll quote in its entirety here: "It should be pointed out that virtually all of the energy from light bulbs of any type is converted into heat. During cold months when a building is being heated, the heat produced by a light bulb is helping to heat the building, and this needs to be taken into account when calculating the energy cost of different types of bulbs. In a typical home using electric heat, for example, light bulbs of any type do not produce any electricity cost during cold months, since the heat produced by the bulbs simply offsets heat that would have been produced by the home's heating system."
Every discussion I've ever seen on the cost of using different types of bulbs always completely ignores the fact that light bulbs do not "use up" any electricity whatsoever, they simply turn it into heat. If the bulb is in a building which needs to be heated, as is true much of the time, then the inefficient old incandescent bulbs can be every bit as efficient as the fluorescent or LED bulbs, since the heat being produced by the bulbs is helping to heat the building. -- Xyzzyplugh 13:04, 24 June 2006 (UTC)
Well, I don't know about you, but using electricity for heating would not be my first choice. Since you usually have to burn something (coal for most of the country) for the electricity, then you are already at 40% efficiency for heating. Using natural gas or heating oil is about 90-98% efficient. If not wasting the heat, then you are wasting you're money. And here in NC, heating costs far less than A/C in sticky summers, so not only is the heat wasted, it would make my A/C work that much harder. -- mjtimber 18:25, 13 October 2006 (UTC)
Does the "Operation removes lightbulb from anus" news link (added with this edit: http://en.wikipedia.org/?title=Incandescent_light_bulb&diff=61329116&oldid=61100085) have any place in the External Links section in this article? I think not, but I thought I should ask before removing it. It seems the point of the linked story is that the guy somehow ended up with an object in his anus, and the fact that that object was a light bulb isn't terribly significant. I think the link adds no value to this article and therefore should be removed. Ra* 23:36, 14 August 2006 (UTC)
Hard to believe you can get sunburn from halogen UV - I'd say it's the heat, not the UV that burns your skin. I added the {{fact}} template, a reference would be nice if this is indeed true. Sure, filtered halogens are used as UV sources (e.g. a dentist's filler hardening light), but the percentage of UV is so small that normally, the glass in front of a halogen is for explosion, not UV protection. (Maybe the writer here confuses halogen with HMI lamps - they produce copious amounts of UV!)-- Janke | Talk 10:03, 1 October 2006 (UTC)
I heard somewhere that the New York Subway used light bulbs with a thread that is a left-handed helix instead of the standard right-handed helix, to discourage people from stealing them and using them. Does anyone have a good reference for this factoid? Perhaps it could be mentioned in the article. Itub 21:14, 2 October 2006 (UTC)
I've been trying to find out the difference between CA, C7, and C9 bulbs. One, or all of them, is the Candlabra kind, but I don't know the difference. These terms may be used in the U.S. only.
Do you think that the redirects at the top of the pages are maybe a bit too confusing? You know you can follow 'incandescent light bulb' to 'lamp (electrical component) to 'light fixture', then to 'stage lighting instrument' And these are all quite substantial articles. I think a disambiguation-type page would make things a lot easier to navigate... Theonlyduffman 07:19, 7 November 2006 (UTC)
This article seems to me pretty lacking when it comes to the physics of incandescence..
all it says is: 'An electric current passes through a thin filament, heating it and causing it to emit light.' It really should go more in depth about the thermal motion of electrons and the fact that they the acceleration of electrons results in emission of EMR. But I'm not the one to write about it as I've only learnt this stuff in my year 12 physics course this year.
Its rather important though... the fundamental aspect of how it functions, which sets it apart from UV lamps, etc.
The german version of the article claims that the following statement about halogen lamps is a common myth: "A tungsten-halogen lamp creates an equilibrium reaction in which the tungsten that evaporates when giving off light is preferentially re-deposited at the hot-spots, preventing the early failure of the lamp." It claims that it is actually preferably deposited at colder spots, and the prolonged liftetime of a halogen lamps is mostly because of their higher pressure. —The preceding unsigned comment was added by 84.173.241.50 ( talk) 18:37, 5 December 2006 (UTC).
Jobrien13057 added chlorine to the list of halogens used in tungsten-halogen lamps. I've reverted that out for now, but I'm more than willing to be proven wrong with a citation. Anyone have one?
Atlant 16:52, 14 December 2006 (UTC)
It the beginning of the article, it says: The current heats the filament to an extremely high temperature (typically 2000 to 6000 K depending on the filament type, shape, and amount of current passed through).
But I'm inclined to doubt this information, as tungsten melts at 3422K, and boils at 5555K, making me think that the filament is never "typically" heated to such a high temperature.
—The preceding unsigned comment was added by 24.147.72.202 ( talk • contribs).
I forget the names myself, but could someone add that to the history.
—The preceding unsigned comment was added by 70.48.39.164 ( talk) 02:53, 4 January 2007 (UTC).
It appears that John William Starr had the first American patent for his carbon-filament incandescent light bulb, but I can't seem to find much other information about him. —The preceding unsigned comment was added by Monstrosity ( talk • contribs) 07:39, 12 January 2007 (UTC).
Many links to www.pegasusassociates.com on other articles were link spam. After removing a link to www.pegasusassociates.com on this article, I wasn't so sure it was link spam, so I reverted my link removal. I'll watch what others do and follow their lead. 24.160.188.24 22:45, 26 January 2007 (UTC)
Is there truth to the rumor that the light from incandescent light bulbs is more comfortable and less damaging to the health of human eyes, than is the light from fluorescent light bulbs? White collar workers who work daily under the light of fluorescent light bulbs report more eye strain? Are the increased medical costs and anguish worth the decrease in greenhouse emissions here? 192.31.106.34 17:18, 20 February 2007 (UTC)
I was looking around at other websites (namely http://www.thehistoryof.net/the-history-of-the-light-bulb.html and http://invsee.asu.edu/Modules/lightbulb/meathist.htm) that claim Warren De la Rue enclosed the platinum filament in the year 1820 rather than 1840 as the article says. Is Wiki wrong? Throktar 05:49, 27 February 2007 (UTC)Throktar
Warren de la Rue must have been something of a child prodigy, because he was born in 1815 and was only 5 years old in 1820. 1840 is the year you're looking for, guys. - Rob Carter -
Yes I noticed this too. But I was unsure if it was even the same person. When I read through Warren de la rue's page, I saw only things about achievements in Astronomy and nothing about the light bulb. I still havn't found a source that says 1840 as the date either. User:Throktar
The section on the halogen lamp should be its own article. There is already a page with that name created in 2002 as a redirect.
This would trim this lengthy article, improving readability and ease of use. A lot of relevant information from this article could also be transcribed over, creating more relevant article for those looking for information on halogen lamps.
Ng.j 15:28, 4 March 2007 (UTC)
Halogen contain bromine and iodine and other halogens not a vacuum in a regular incandescent bulb
Halogen are generally sold specifically as halogen, and function differently than regular incandescents. They are also banned many places where normal incandescents are not (for example, most college dormitories) 67.94.175.114 20:54, 15 June 2007 (UTC)
Hey - this is my first post, so be gentle on me. I'm not quite sute how all this works. All I wanted to say was that Australia has not banned the incandescent light globe as stated in the introduction to the article. EJH69 07:38, 22 March 2007 (UTC)
Someone recently removed the brackets [ ] from the the convenience links to online sources. The practice I am familiar with is to put the brackets around the html link and then to have text outside the brackets identifying the source. With this, the weblink, which may be quite long, appears in the reference section as a colored number, and the verbal description appears as black text. Is there a convention to just have the weblink and the description of it between the <ref> and </ref> in the inline cite in the text? I reverted to the previous version pending discussion. Edison 23:54, 12 March 2007 (UTC)
It is a shame that lighting efficiency is such a complex technical subject! It seems like the one thing people could most clearly agree on and understand is what percent of the energy supply turns directly into heat, so these numbers should be listed. But what ordinary folk most want to know is, what percent of the energy supply is emitted in the visible spectrum, from the light fixture as a whole. The complexities of adjusting that number to compensate for the sensitivity of the eye to various frequencies leads to numbers that should certainly be mentioned, but not as the only or even primary numbers here. (If a black box turns all of the electricity supplied into emitted orange light, to me that is 100% efficient. If another box turns all of the electricity supplied into emitted purple light, to me that is 100% efficient. If a scientist considers one to be more "efficient" than the other, because the eye sees purple better or worse than orange, that would be interesting to know, but would not change the fact that each is basically 100% efficient.)- 69.87.193.242 15:31, 4 April 2007 (UTC)
Incandescent bulbs have a low resistance when cold, about one-tenth of the hot resistance. So, when they are turned on, they use about ten times as much power for an instant, until the filiment gets hot.- 69.87.193.242 15:31, 4 April 2007 (UTC)
Often, when an incandescent bulb is at the end of its life, it will keep working if left on and not disturbed. But after being turned off and cooling down, it will then fail immediately (sometimes with a flash) when turned on, due to the stresses of thermal shock and various changes caused by power cycling.- 69.87.193.242 15:31, 4 April 2007 (UTC)
You could take a short sequence with the correct exposure of filament off, then adjust to the correct exposure for filament on" and power it up. It would also be possible to illuminate the filament with another source (like a slide projector) and focus the light on the filament in the "dark" frames to reduce the brightness change. Some incandescent bulbs "sing" at a high frequence when on. The support locations probably help define the frequency. Edison 23:07, 10 April 2007 (UTC)
Has anyone any solid proof that incandescent bulbs have been banned anywhere in the world at all? The existing section lacks such evidence, and only talks about proposals and possibilites. Should the whole section be deleted or re-written? I think most if not all the proposals are political spin, and quite unreal. There are rumours that one CFL maker (Phillps in Holland) is trying to push politicians in europe to ban the bulb (!) so that it can reap vast profits from its CFL arm. Peterlewis 14:51, 6 April 2007 (UTC)
Those alleged plans are simply spin and political hype. I have seen no substantial and well based government reports at all. All the current refs in the article are newspaper reports or based on environmental sites which have an agenda to pursue. Any government sites have very limited advice. Wki should try to keep a neutral base for its articles, and not simply push a political agenda. Peterlewis 12:41, 11 April 2007 (UTC)
It depends how you define efficiency. 100% of the electricity coming into my home for lighting ends up as useful energy. If you widen the system to include the power station, you will find that some power stations use the waste heat for space heating elsewhere. The Scandinavians and Russians are very good at using waste heat in CHP systems.
Peterlewis
16:16, 11 April 2007 (UTC)
I know it to be a fact that Germany after 1933 propagated the view that Jews could not be trusted. Are you seriously expecting Wiki to air such view (if Wiki existed in the 1930s)? You must be very naive if you expect citizens to believe what their governments tell them. Why should Wiki act as their mouthpiece? Wiki must stand by verifiable facts and not hide behind government statements or websites. If you must put your own POV, then you have to accept that others have a different viewpoint, and that their views need representation. Peterlewis 19:05, 11 April 2007 (UTC)
Why is much of the introduction to this page on Incandescent light bulbs talking about CFLs?
I realise they are mentioned in relation to proposed laws in a handful of jurisdictions to ban incandescent lights, but surely there info that is more relevant that should be placed there. Most of the last paragraph sounds to me like little more than an attack piece against those proposed laws than anything relevant to a factual article. Canderra 16:48, 30 April 2007 (UTC)
"Higher wattage bulbs tend to be more efficient than lower wattage ones. One reason for this is the fact that thicker filaments can be operated at a higher temperature, which is better for radiating visible light. Another reason is that since higher wattage bulbs would lead you to use fewer bulbs, you buy fewer bulbs and the cost of bulbs becomes less important. To optimize cost effectiveness in this case, the filaments are designed to run hotter to improve energy efficiency to reduce your electricity costs. Smaller bulbs use less electricity apiece, making the cost of the bulb more important. This is why lower wattage bulbs are often designed to last 1500 to a few thousand hours instead of 750 to 1000 hours. Designing the bulbs to last longer reduces their light output and energy efficiency." [19]
Please add lumens/watts for typical 4W/7W E12 candelabra nightlight bulbs. Explain why lower wattage bulbs are so much less efficient. Add good links to collections of real spec sheets...- 69.87.204.2 20:42, 15 May 2007 (UTC)
There is a lot of content about halogen lamps - looks like it could be spun out to get this article down in size and not so rambling in content. -- Wtshymanski 23:37, 18 May 2007 (UTC)
Are the output etc statistics given (and that appear on the labels in the stores) for a new bulb, or typical averages over the service life? Over the service life, how does the output (lumens) and efficiency (lumens per watt) vary, for ordinary 40-100W 120VAC bulbs? It seems like as the filament evaporates, the bulb would become more like a lower-wattage bulb, and have higher resistance, emit less light, and be less efficient in lm/W -- is this correct? How large is the typical change? Where is there more data about this? Eventually, if we want to compare different lighting technologies fairly, we need to be discussing typical average performance of the life of the device/product/system, not just "maximum when new" claims.- 69.87.201.16 11:20, 25 May 2007 (UTC)
"The average light output of a lamp over its rated life. Based on the shape of the lumen depreciation curve, for fluorescent and metal halide lamps, mean lumens are measured at 40% of rated lamp life. For mercury, high-pressure sodium and incandescent lamps, mean lumen ratings refer to lumens at 50% of rated lamp life (See Lumen Maintenance)."
"A measure of how well a lamp maintains its light output over time. It may be expressed numerically or as a graph of light output vs. time."
[20]- 69.87.199.232 13:17, 19 June 2007 (UTC)
(there are said to be about five billion light bulb sockets in North American households -- if we can pin down and source some such statistic, it should maybe be in the intro)
We need some photos of prism-separation of incandescent light.
These are interesting resources:
- 69.87.203.221 02:04, 26 May 2007 (UTC)
Yellowish-white light emitted in all directions. Available in either clear or frosted. Types: General (A), Globe (G), Decorative (D) (flame, teardrop and other shapes)
Reflective coating inside the bulb directs light forward. Flood types (FL) spread light. Spot types (SP) concentrate the light. Reflector (R) bulbs put approximately double the amount of light (foot-candles) on the front central area as General Service (A) of same wattage.
Parabolic Aluminized Reflector (PAR) bulbs control light more precisely. They produce about four times the concentrated light of General Service (A), and are used in recessed and track lighting. Weatherproof casings are available for outdoor spot and flood fixtures. 120V (PAR) 16, 20, 30 and 38 bulbs: Available in numerous spot and flood beam spreads. Like all light bulbs, the number represents the diameter of the bulb in 1/8s of an inch. Therefore, a PAR 16 is 2" in diameter, a PAR 20 is 2.5" in diameter, and a PAR 38 is 4.75" in diameter.
-- Halogen Bulbs are available in two distinct voltage types - 120V AC and 12V AC/DC. 12V MR16 and MR11 bulbs are available in multiple color temperatures.
Types of Bulbs and Their Usage
"HIR" means that the bulb has a special coating that reflects infrared back onto the filament. Therefore, less heat escapes, so the filament burns hotter and more efficiently. [21]
[22] - 69.87.199.232 13:42, 19 June 2007 (UTC)
I hope nobody objects to the reversion of the following line "During WWII, Hitler liked to burn jews and use their ashes to reduce oil usage." from 209.129.155.253 of the California State University Network. Kesmet 21:33, 20 July 2007 (UTC)
Nobody would object except perhaps 209.129.155.253. Revert this sort of stuff quickly, freely and without prejudice. And don't bother entering a Talk page item. Just do it! Jim77742 11:01, 6 September 2007 (UTC)
I reverted an edit which removed a reference which stated that Edison's was the first "practical" light bulb. Let's discuss what constitites an incandescent electric light, and what factors make one practical or not. The determination is not really up to an editor; it should be cited to reliable sources who say a bulb was or was not a practical incandescent light. As soon as the battery was invented, around 1800, experimenters noted that electric current of sufficient amperage would make metals such as platinum (favored for its high melting point) and the nonmetal carbon glow brightly. The arc light was demonstrated by Davy before 1810. When the thin carbon rods of the arc light were touched together to start the arc, they glowed brightly: they became literally incandescent before they were drawn apart and the aarc light was exhibited. If the conductor glowed brightly, it soon burned out, so it was a nice demo for a science class or to show a newspaper reporter, but not yet a practical light. A reporter could be impressed by a wire glowing red, but it would not be a satisfactory or practical light. If there were any oxygen left in the enclosure, it would soon burn out, and in any event the carbon from the heated rod would soon darken the glass. I say "rod" because generally early experimenters gave no thought to the need for a high resistance carbon filament, to allow powering a light from a central generating plant. They just connected a huge and expensive battery to a nearby conductor, made it glow for a few minutes, and voila. No one stood watching the demo 24 hours a day to notice that the glowing conductor only lasted perhaps one evening, like a candle wick made of platinum. Getting a patent on an incandescent electric light in the 1840's or 1850's does not constitute reducing the idea to practice. Swan and Edison in the late 1870's were the first to create incandescent lights that had any degree of practicality, as opposed to replicating the demonstration from the beginning of the 19th century that electric current makes a conductor glow for a while, until you increase the current to get near-white incandescence, soon after which it would burn out. Swan and Edison both have claims to fame in the development, but Edison accomplished a better product sooner, partly because of his greater research budget. See above under "Warren De la Rue's date is wrong?" for more references countering claims that earlier experimenters were the "true inventors." It is hard to document accomplishments of De la Rue because sometimes sources say De la Rive. Both experimented with electricity. Several experimenters were brought forward in patent litigation of the 1890's to make hard to substantiate claims of prior research (just as happened with the telephone). Edison 22:38, 5 September 2007 (UTC)
Whew. I've tried to remove some of the excess fuzz and lint from the article. Surprisingly, it only got about 4 kb shorter. I think it's better organized now - comments, please? But three hours at a time is about all I can stand. How long before it needs another clean-up? I really think the "ban the bulb" section should be sput out into a separate article if it needs to be represented at all; it's just a list of press releases at this point. We need more content - how about colored lamps? Rough-service bulbs? So-called long-life bulbs? -- Wtshymanski 16:31, 20 October 2007 (UTC)
Moved contents to Incandescent lamp, since this is the professional term of art for this type of lamp (and it is consistent with the names of other types of lamps). "Bulb" is a colloquial term, like "globe." I didn't know what to do about the discussion, so I left it. Agateller 12:10, 1 November 2007 (UTC)
Note that pages may not be moved by cutting and pasting text from one to another. Pages must be moved with the "move" button. Nontrivial moves must be cleared first through the process described at Wikipedia:Requested moves.-- Srleffler 17:49, 1 November 2007 (UTC)
but modern exit signs must use LEDs)
Fluorescent emergency exit signs are the standard equipment in most of the world.
Most safety codes now require halogen bulbs to be protected by a grid or grille, or by the glass and metal housing of the fixture to prevent ignition of draperies or flammable objects in contact with the lamp.
nope. With just 0.3 of the 6+ billion people on the planet, America is just 5% of the world population. Tabby 14:29, 11 November 2007 (UTC)
I believe that there should be a link under the title along the lines of "Lightbulb redirects here. For Fluorescent bulb, click here. -- HobbesDS ( talk) 02:09, 7 January 2009 (UTC)
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 | Archive 2 | Archive 3 | Archive 4 |
More than half of the introduction for incandescent light bulbs is talking about switching from them to CFLs. This seems completely bizzare and out-of-place. 69.141.68.106 01:21, 23 May 2007 (UTC)
...not spontaneous emitters. The following:
"As the electrons that travel through the filament bump into the atoms, some of the electrons in the atom may become excited. This means they temporarily boost its energy level and raise to higher orbit. When they fall back, energy is released as photons, a photon being the particle form of light."
is true, but the vast majority of the light comes from blackbody radiation, which isn't even mentioned. I guess this is what happens when you copy from howstuffworks.com... 168.230.48.248 03:25, 5 July 2006 (UTC) (Andrew)
I agree - as a physics graduate, incandescent bulb spectrums are NOT shaped primarily by electron transitions in **atomic** tungsten. This is somewhat misleading and is wrong if you're trying to explain how an incandescent bulb gets its light spectrum. Black body radiation accounts for most of the spectrum's (continuous) shape and is also the reason why incandescent bulbs tend to look very natural to the human eye compared to other types of lighting - the sun's light is mostly shaped a lot by black body radiation too! Though electron transitions facilitate blackbody radiation, it's not the atomic structure of tungsten that provides the spectrum. I've reworded this. Physicists please check that I've given a correct explanation. 18.250.0.177 15:02, 8 November 2006 (UTC)
In revision 139201 an anonymous user inserted a large block of slightly modified text from external websites ( [1], [2], [3], [4]). The contributor that did this seems to have copied passsages of text from several different wesites and pasted them together with minor to moderate rewording of some sentences. This is not covered under fair use. Fortunately, others have since copyedited the text and have obscured much of the obvious parentage. More is needed however. Please keep this in mind while editing. -- mav
Hey, I'm all kinds of new here, but is there *any* substantiation to this "modern lightbulbs filled with inert gas" buisness? I know we have neon lights, but the article seems to imply that modern incandescent bulbs are not evacuated, but any good (although not safe, and not reccomended) smashing of lightbulbs proves that they are at least nearly evacuated. -j
Be careful using a shatter test on 'neon' lamps. If you get a cut it can take a long time to heal due to the chemicals used to coat the inside of the glass. At least so I have heard.
Plus, drops of liquid mercury and other nasty chemicals in fluorescent lamps likely turn to minute droplets and go airborne when the tubes are smashed.
The whole paragraph about Davy's work could stand to be rewritten, preferably by someone who has consulted contemporary sources.
Edison 21:22, 20 June 2007 (UTC)
The article Light bulb says in section History of the light bulb
I assume (not much of chemist, i) that oxidation of Pt is unlikely, and that this misinterprets Lights by Edward Willett, or something similar, which refers to
I say "oxidation ... unlikely" in the belief that Davy chose Pt bcz that (and maybe Au) were the only things he could find that didn't oxidize when incandescant (and maybe bcz Au melts a lot earlier).
Here are some #s from WP:
Parameter ---------- W ----- Pt
Melting point --- 3695 K 2041.4 K
Boiling point --- 5828 K 4098 K
ρ-1 (106/m ohm) -- 18.9 09.66 (or should i be suspicious of the leading zero?)
At. wt. (amu) --- 183.84 195.078
What i understand to be the main failure mechanism in ductile-tungsten filaments is the positive feedback at the hottest points, of
culminating in local melting across the whole cross-section, of enuf length that sag (or just instability?) lets the liquid portion flow away from its center. (Haven't noticed if that's in the article; it should be IMO.)
IMO, the presence or absence of air doesn't make a lot of difference in that kind of failure, bcz even if convection is more efficient for the first few inches than radiation alone, incandescence is required, and the operating temperatures are going to be essentially the same.
With Pt in the same geometry such failure just happens sooner; i imagine much sooner: i base that on the principle that chemical reaction rates go up very rapidly with temperature bcz they are controlled by the population in excess of the activation energy, which increases much faster than mean energy, and on my belief that thermal migration should similarly limited by an activation energy representing a surface atom breaking all but two (or if not, all but one) of its bonds, so it can swing to its next position.
The higher conductance of W (which surprises me, but whadda i know) does mean the Pt filament has twice the cross-section area for the same length, voltage and current, but that may not be what determines the geometry: with modern W, it may be economical for filaments to be made thicker and longer (for ruggedness and reduced thermal-migration failure, but with Pt the cost of filament material has to limit the feasible increase of dimensions. So i think the lower conductance is completely swamped by the melting point and perhaps dimension issues, and i am convinced the same non-oxidative failure mechanism can explain Davy's results. -- Jerzy '03 Dec 15
Thx! On reflection i agree. I may have been searching for my keys under the street lamp, esp since i despair of having any hope of estimating sublimation rates, either relative between materials or relative to the solid-state thermal surface migration -- other than to note that activation energy for sublimation has to be higher than for surface diffusion. Maybe i should have taken another thermo course or four.
I think sublimation can also participate in the feedback loop, but at least initially it promotes a graceful degradation, with the bulb getting cooler (and dimmer) as the filament thins and delivered power drops.
(My first thot on reading the sublimation contrib was "Ah, then the bulb maintains a vapor pressure of the filament material, and makes a difference other than via restricting convection to a remote heat-flow mechanism." No, fool, the bulb just makes it obvious that sublimation is a second thermal-migration mechanism that you didn't even consider: thermal migration via gas phase to the sub-incancesent bulb instead of via solid phase within the filament. 'Scuse me, gotta go off and cry somewhere.) -- Jerzy 19:41, 2003 Dec 16 (UTC)
Don't be too hard on yourself, Jerzy. You were right to dispute the "oxidized" claim (which I just changed).
Looking into this further, I think sublimation may be a less graceful degradation mechanism than you say, but I'm not sure. For analytical purposes, I imagined a filament divided into 100 segments in series. For a 240 V 100 W bulb (common here in Britain), I calculate the filament resistance when hot to be nominally 576 R. In my scheme that's 100 5.76 R segments in series. If, due to evaporation, one segment doubles in resistance to 11.52 R, then the total filament resistance will increase by 1% to 581.76 R. With the same supply voltage, the power will drop by nearly 1% to 99.01 W. As you said, this will cool the bulb and help to slow down the evaporation. On the other hand, think what happens to the thinned segment. The current through the filament has now dropped by 1% (from 0.4167 A to 0.4125 A), but the resistance of the unfortunate segment has doubled, so the power in that one segment has now increased by 96% (from 1 W to 1.9606 W), making it evaporate much faster! It seems that the increase in local power dissipation will strongly dominate the slight decrease in global power dissipation, causing a runaway failure, but I haven't proved that this is true for all cases.
If you have been, thanks for reading this far! -- Heron
A big issue i keep coming back to, tho, is that we'd like to find phenomena that work when the non-uniformities are infinitesimal. I think your example points out the fact that power goes up faster than segment resistance, because P = VR2, which enhances the feedback, at least once the uniformities get large. But what i'm starting to worry about is that unless we're talking about irregularities that are there from the factory machining, they are likely to be swamped by the thermal noise. IMO there are some things that work against the feedback: i think infinitesimal surface roughnesses are subject to negative feedback: atoms at convex surface points are bound to fewer atoms and therefore (i think) less strongly bound; atoms at concave surface points by the same token more strongly bound. We therefore expect the background surface diffusion (the component not driven by temp differences) to favor moving atoms from convexities to concavities, and smooth out the surface. Gets more complicated as we examine more closely, i fear.
It sounds, tho, like you know no more than i abt how hard it is to oxidize Pt at those temps, & i fear our alternate failure mechanism (instead of fairly uniform erosion (or resistance increase, on the assumption that the oxide is non-conducting but non-volatile), by oxidation) is irrelevant - i.e., if there's nothing wrong with the previous editor's oxidation hypothesis!
What i haven't done is finished searching the web for statements that Davy's Pt failed by oxidation; i've been treating the suspicious text like a smoking gun, but there may be a more credible source out there that says "oxidation" explicitly.
Interesting, nonetheless. [smile] -- Jerzy 03:28, 2003 Dec 17 (UTC)
You are right to say that I don't understand the chemistry of what's happening. I will leave that to someone else.
"The Invention of the Incandescent Lamp" by Globusz Publishing, among other web pages, points out (in somewhat convoluted English) that the temperature at which platinum glows is very close to its melting point, which is what makes it so unreliable. I think this is the (disappointingly simple) answer. -- Heron
I hope you will not mind if I throw my two cents in.
The failure modes of incandescent lights has interested me too. I think evaporation is an important failure mode, and you can confirm this by noting that high intensity bulbs build up a dark layer on tungsten (or whatever) on the inside of the bulb as they age. The halogen cycle helps slow down this loss. The bulb temperature must be very high though for this trick to work. This is why quartz glass must be used. Halogen lamps intended for projection use are rated for 50 hour life and are specified to operate at about 50C below the melting temperature of tungsten. The melting temperature of tungsten, I believe, is closely related to, and limits, the quoted "color temperature" of tungsten light. I believe that lamp lifetime varies with the sixth power (I forget, but the effect is big) of operating voltage, and I could look up the empirical derating formula if anyone cared.
What I really wanted to offer, though, is another observation. I believe that it is common for lamps to fail at the moment they are turned on. I have noticed that when incandescent lamps are dimmed very low using a phase control dimmer that they emit a noticable sound. I believe that tungsten lamp electrical loads draw a nominal 10x current surge when the load is first turned on, that is, the rule of thumb for sizing switch contacts, etc. is to expect this much surge. I believe this is due to the cold filament having a much lower electrical resistance initially. Careful examination of the phase control circuit waveform shows that there is an enormous, short duration current spike on each half cycle as the partially cooled filament is connected to a relatively high voltage, instead of the normal smooth sinusoidal voltage buildup. I believe that some of the corresponding noise may be from thermal distortion as the filament heats rapidly. However, I suspect, that some of the noise may be due to forces created by the rapidly changing, 10x magnetic field around the (usually) coiled filament, due to the current surge, acting on the conducor. I think this magnetic effect may also account for the tendency of the bulb to fail as it is turned on, by adding one more stress to the cold and weakened metal.
Quoth the article:
This is quite different from the Davy lamp described in the linked article (basically, a safety mechanism for an open-flame "lamp" that allows it to be used in mines where flammable gasses may be present). Is the description of the lamp here wrong, or is it not the same lamp that came to be known as the Davy lamp, or is the other article at fault, or what? The other article _feels_ more reliable to me than this one, but that's a highly subjective assessment made without any real background in the subject matter, and in any case even if the Davy lamp article is assumed correct it is not obvious how to rectify this (incandescent light bulb) article. The section probably ought to be flagged for reworking, but I'm not sure which tag best applies. For now I have used the "Not verified" flag; feel free to replace it with a more appropriate one if such exists.
I was browsing around and came across a guy's rant [11] which also includes a lot of great info on light bulbs. I'm not sure if it's proper to include as an external link, though.
I see that light bulb redirects to incandescent light bulb. I think it should go the other way around -- this article discusses flourescent, carbon arc, and other non-incandescent lights. So I think this article should be titled simply "light bulb". Should we simply move the article, or would it be better to split it up into a general "light bulb" article and a specific "incandescent" article ? -- DavidCary 03:08, 10 Sep 2004 (UTC)
Please note that most of the articles use the noun "lamp" rather than light. So if you're going to move this, it would probably be better to move it to "Incandescent lamp" rather than anything named "... light".
Atlant 13:01, 17 Dec 2004 (UTC)
Now I'm confused. My recollection was that MES was minuature Edison screw, the standard torch (flashlight) bulb, and that LES was liliputian Edison screw, an even smaller bulb used in torches and as indicator lamps (in the days before LEDs). But the article uses MES to mean medium Edison screw, the standard light fitting. I always thought this was just ES. Also pretty sure I've come across things described as SES (small Edison screw) -- perhaps this is equivalent to the candelabra fitting mentioned? Or perhaps I'm just confused Roy Badami 18:33, 28 Mar 2005 (UTC)
Article says "the E stands for Edison, who created the screw-base lamp, and the number is screw cap diameter in eighths of an inch in the U.S." This does not compute, as that would mean an E26 is 3.25 inches in diameter (8.3cm). Thirty-seconds of an inch would make more sense. I'm going to take out the "eighths of an inch" until a better explanation is provided. ---Ransom (-- 208.25.0.2 16:53, 9 May 2006 (UTC))
It would be useful to include a bit about what Type A, Type B, etc. bulbs are. The article only discusses the screw fitting, but many manufacturers refer to Type A bulbs...
LEDs are much more efficient than the stated 20lm/w. see: http://www.lrc.rpi.edu/resources/news/pressReleases/spemethod.asp
Not true - at least, not true for white LEDs. Depite the hype that pervades the industry about the future potential efficacy of LEDs used for lighting, the actual specs of real-life LED products for lighting applications is in the range of 20 - 25 lumens per watt. This is less than one third of the efficacy of compact fluorescent bulbs. You can verify this by checking the specifications of products of leading high-brightness LEDs from manufacturers such as Lumileds:
http://www.lumileds.com/pdfs/DS45.PDF
Colored LEDs may be quoted with higher efficacies because green and adjacent colors sit at the peak of sensitivity of the eye. However, this is no indicator of their usefulness for general purpose illumination. You have to be looking at the white-light specs in order to do an apples-for-apples comparison with other white light sources such as compact fluorescent.
Well, my grandmother in Pennsylvania calls them light globes, so the above claim is too strong. I always figured it was a largely obsolete term from her youth, that has fallen out of favor in the U.S. Anyone else know of "light globe" being used outside of Australia and S.A.? -- Coneslayer 15:09, 2005 July 28 (UTC)
Maybe someone can offer some insight here. The spectra that I recently uploaded of a (unfiltered, clear) flashlight bulb [12] appears to have a peak emission of around 630 nm. However this [13] says the filament should therefore have a temperature of ~4600K which is clearly impossible.... Does the glowing filament deviate from a blackbody that severly as to make an approxamation like this impossible? What happened?-- Deglr6328 06:39, 5 September 2005 (UTC)
There seem to be several sections in this article that independently make comparisons between Incandescent bulbs and various other types of lighting. eg. Comparison of electricity cost compares with the cost of compact fluorescent, Efficiency compares with a bunch of other types, Heat makes comparisons with compact fluorescent lights, and so on. I was wondering if it'd be beneficial to have a separate article to consolidate comparisons between lighting types... or maybe it could be part of the light bulb article (mentioned above), or the lighting article.
I've worked on the light pollution article a lot recently. I started drawing a table comparing different types of lighting, but then began wondering such a list really belonged there. For one thing, it seems to be duplicating a lot of lighting information available in many of the different lighting articles, just as the comparisons in this article probably duplicate the same information elsewhere. Does anyone have any thoughts about this? Izogi 07:34, 6 September 2005 (UTC)
I wondered if the tungsten use was an alloy or pure (mostly) tungsten? Anyone know?
Efficacy might be a correct term, but to me it seems less specific than energy efficiency, and the linked efficacy article doesn't (currently) seem to or address the idea at all. On the contrary, it's very weighted towards psychological meanings, with small cameos for medicine and politics. It isn't anywhere near as helpful as the energy efficiency article was. The efficacy article could almost be a disambiguation page, or have some redirect text at the top to point people at energy efficiency if they want something about energy. Anyway, I'm not quite sure what the best approach is here. I'd quite like to point the links back to energy efficiency, because it seems to be more specific and it is a more widely recognised term, in my opinion. In the interests of avoiding an edit war, though, does anyone have any strong opinions on this? Izogi 22:24, 9 September 2005 (UTC)
But what was incorrect about energy efficiency in the first place? I just think it's clearer, not to mention more specific. Izogi 08:15, 10 September 2005 (UTC)
Fine with me. Izogi 21:37, 10 September 2005 (UTC)
The heading "efficiency" in the table is incorrect and misleading. The percentage figures in that table express the lumens delivered by one radiated watt as a proportion of the theoretical maximum of 681. They depend only on the shape of the spectrum and they do not account for any "efficiency" concept whatsoever. To use the term "efficiency" in this context is misleading - well, actually not misleading - just plain wrong. Using the term "efficacy" is also wrong because that's a clearly defined term and this isn't it. I am not aware of any properly defined term that describes the figure shown in that column so I can't offer a solution - I only offer that "efficiency" is NOT the correct term.
When you go to "Incandescent light bulb" from the Search it gives you this: The invention of the light bulb is usually attributed to Amanda "Mugsy" Emms, who contributed to its development by producing a practical and viable electric lamp. However her invention was stolen by Thomas Edison who marketed the device successfully. Alexander Nikolayevich Lodygin developed an incandescent light bulb around the same time. Many others also had a hand in the development of a practical device for the production of electrically powered lighting.
But when you go to "Light Bulb" from the search it gives you this: The invention of the light bulb is usually attributed to Thomas Alva Edison, who contributed to its development by producing a practical and viable electric lamp, and marketed the device successfully. However, it is now believed that Heinrich Göbel built functional bulbs three decades earlier. Alexander Nikolayevich Lodygin developed an incandescent light bulb around the same time. Many others also had a hand in the development of a practical device for the production of electrically powered lighting.
I honestly don't know much about the lightbulb so I'm not going to correct it on a hunch (no matter how big), but I've never heard of the Amanda Emms version of the story. Also why is there two different pages that claim to redirect to the same place [Incandescent light bulb]? -- Taboo Tongue 20:13, 19 November 2005 (UTC)
It's my understanding that the Woodward and Evans light bulb did in fact work and that Thomas Edison thought that their approach was sufficiently promising to buy rights to their patents. I am not an expert in the field, however. My source is [16]. I would gladly defer to another who is more expert or who can provide a more authoritative source. On another note, what's the point of emphasizing that Woodward was not a "gentleman" (presumably a noble?) but "merely" a hotel operator. It may be true, but unless it's relevant to the history of the develpoment of the light bulb, I recommend that that fact be removed.-- Nowa 00:15, 21 December 2005 (UTC)
Thomas Edison has been nominated on WP:IDRIVE. Vote for this article and help improve it to featured status. -- Fenice 14:02, 26 December 2005 (UTC)
There are too many links, especially in the intro paragraphs, and some ("archaically"?) are not really relevant to the context. See Wikipedia's style info on this. I'm taking out links to some plain English words and irrelevent words. Benhoyt 03:10, 6 March 2006 (UTC)
I have changed the comparision of electricity cost to reflect more accurately the lumen output of a CFL. 13-15w CFL's output 800-900 lumens. In the range of a 60W lamp. See http://www.energyfederation.org/consumer/default.php/cPath/25_44_785 for an excellent sampling of CFL wattages and lumen outputs. The existing references also support ~14w CFL =~ 60w incandescent.
Now I'm no expert however I've been purchasing light bulbs for a while and I'm pretty sure the expected life time of a CFL one and an incandescent one is roughly the same, this is ofcourse greatly company dependent but if someone with the education could confirm and/or correct this?
Here in Norway (and Sweden?), the normal average lifetime for an incandescent lamp is 2500 hours. This is confirmed by independent tests (text in Norwegian), and a 40 W bulb brand with such lifetime was measured to emit 396 lumen on average, which seem to compare fairly to US bulbs. Osram, the manufacturer, makes lamps in their German factory rated at 1000 hours, and claims the longer life of the lamps made in Norway is due to special regulations! I wonder why the rest of the world doesn't copy our regulations... -- Kjetilho 00:40, 1 August 2006 (UTC)
The section on Power (as well as comments above) provides helpful information regarding long-life (130-volt) bulbs. However, it's not clear whether the chart in the Power section ("Comparison of efficacy by wattage") assumes these bulbs are operated at 120v or 130v. Hopefully the former, but in any case the assumption should be stated in the explanatory text next to the chart.
It makes no sense to define an efficiency percentage of a light bulb without a certain reference, since you cannot divide lumens by watts and get percents out. If you have a hypothetical light source that converts 1 W of electrical power into 1 W of light at 675 nm (typical wavelength for red laser pointers), then the energy efficiency of this light source is 100% (1 watt useful output per watt of input). However, according to the definition in the previous version (perfect monochromatic light source at 555.6 nm is 100%), the efficiency would be 2% and the other 98% are, as written in the beginning of the article, "wasted as heat". I don't think it is appropriate to call this "wasted as heat" just because the eye is a less sensitive to this wavelength than green 555.6 nm light. The appropriate way is to take the ratio useful output power (in watts) and total consumed power. One way to do is to take the part of the power which is emitted in the visible range, i.e. 420 to 700 nm (see luminosity function), in order to not count infrared and ultra-violet radiation. However, this would give too much weight to the almost-IR and almost-UV parts of the spectrum, and give an incandescent lamp a much higher efficiency than it deserves. Since the table is about efficiencies of sources for illumination, it has to evaluate light sources with a fairly broad spectrum. A light source that converts electricity into visible light in the range 420-700 nm cannot have an efficiency higher than 242 lm/W due to the fact that the eye needs other wavelength components than just 555.6 nm green in order to get the impression of a white light source. It is possible to calculate the optimum spectrum that will give you most lumens per watt while still give you daylight white rather than green. I don't know where exactly the 242 lm/W comes from (the original link pointed to an irrelevant page), but it seems quite reasonable judging from the shape of the luminosity curve, e.g. the number of lumens if you take one watt of flat-spectrum light in the range 420-700 nm.
So, to summarize: if the best possible spectrum that looks like white gives you 242 lm/W, then this should be considered the 100% efficiency point of an illumination device —Preceding unsigned comment added by hankwang ( talk • contribs)
I agree with hangwang's changes to the table. This brings it in line to what my college physics book says for the efficiency of incandescent and CFL lights. Perhaps the terminology needs to be clarified, but as far as the percentages go, they should remain as Hangwang has them. Perhaps the ideal monochromatic source should be removed. Why use pure (monochromatic) green light as a reference? TimL 15:39, 16 April 2006 (UTC)
Furthermore, the definition of Luminous efficiency is total lumimous flux over total radiant flux. So for both ideal white light source and monochromatic (555.4nm) source the correct percentage value would be 100%. I am now going to make this update. TimL 15:52, 16 April 2006 (UTC)
Leaving aside for the moment the issue of whether Hankwang's argument is correct, his reversion was not a good edit. If you look more closely, you'll see that I made a number of other changes, including carefully going through and fixing the references, which were messed up. The reason one of the references seemed irrelevant was because edits had caused the footnote numbering not to correspond to the correct notes. (This was a problem with the old footnote system. I changed the table over to the new footnote system.) The other problem is that, independent of what definition of efficiency Hankwang feels is appropriate, the definition of luminous efficiency used in his version of the table did not agree with the definition in the article text.
Now, as to the technical issue: What needs to go in the article is not what Hankwang things is best, but what is actually used. If someone can cite a reference that defines luminous efficiency, that would be justification for changing the table. Otherwise, I propose we keep what we had. I need to revert the edits to fix the references. If you want to change the numbers please edit the table instead of reverting it back to the version with the broken references. But, please provide a reference that justifies this change in the contents of the article rather than an argument about what seems best.
Even in terms of what seems best, though, the arguments above are incorrect. A monochromatic green source has higher luminous efficiency (and efficacy) than a white light source because if you compare two sources with the same power the monochromatic source will seem much brighter. You can see better by the source with the higher efficacy. To use Hankwang's example above, it's perfectly reasonable to say that the luminous efficiency of a 675 nm source is only a few percent. Anyone who has ever compared a 1 mW red laser spot to a 1 mW green laser spot knows this. Similarly, a monochromatic green source is brighter than a white light source of the same radiant flux. It's not great for illumination because it isn't white, but such sources are used. Ever seen a green LED nightlight? They are very energy efficient, and yet you can see quite well by them. In general, Hankwang's argument seems to not understand the purpose of the luminosity function or of luminous efficiency. Hankwang also seems to confuse "efficiency" and "luminous efficiency". These are not the same thing. Efficiency is about how much light is emitted, vs. how much is wasted as heat. Overall luminous efficiency is about how much of the energy consumed produces something that is useful for vision. Red light is less useful for vision than green light. White light is less useful for vision than green light too (in the sense that the latter is brighter than the former, for equivalent levels of radiant flux.) -- Srleffler 03:47, 17 April 2006 (UTC)
The comment for this edit should have read "100% is the maximum possible value for luminous efficiency." TimL 15:54, 16 April 2006 (UTC)
This lists glass halogen (2.3%), quartz halogen (3.5%) and tungsten-halogen (2.6%-3.6%). It seems like we have some overlap here in terminology, creating a longer table than necessary. (I also don't see how we need three rows for LED's but thats another story). Aren't glass halogen and quartz halogen two types of tungsten halogen lamps? Seems to me like we could do with just listing quartz halogen, or tungsten halogen.
About white LED's, since it is both a rapidly devloping and emerging technology, perhaps we could just have a footnote at the end of the table mentioning their possible efficiencies. TimL 04:01, 18 April 2006 (UTC)
Looking at the Klipstein reference for LED prototypes I found little evidence except for a very vague press release from Cree regarding 100 lm/w led. The press release refers to 'results', not any actual working prototype. I have created a new reference that talks about a prototype LED that procuces 80 lumens per watt, but only at extremly low currents. I also saw at the Klipstein page nothing about high vs. lo0w power LED's. So I removed the Low power line. In fact the chart on the new refernce I created suggests that LED's have a higher luminous efficiacy at low power. TimL 21:58, 19 April 2006 (UTC)
Edison 14:00, 2 April 2007 (UTC)
What does the following sentence mean?
Bamboo continued to be used until 1893, later enhanced by a cellulose coating, introduced around 1882 and produced until at least 1929.
Bamboo was obviously used without cellulose coating until 1882. From that year, it was coated in cellulose, but what happened between 1893 and 1929, when bamboo use had supposedly ceased, but cellulose coating had not? LX 06:05, 20 April 2006 (UTC)
Could be insert also the contribution to this invention by the italian scientist Alessandro Cruto? HI
-- 80.104.130.37 10:47, 8 May 2006 (UTC)
What is it about a fingerprint that destroys a quartz halogen lamp? According to http://www.its-90.com/al-sil.html, (last section, "PRECAUTIONS TO PREVENT DEVITRIFICATION OF QUARTZ ENVELOPES"), "Fused quartz is vitreous in nature but, like other glasses, can be stimulated to crystallise (devitrify) by external influences at high temperatures.... Sealed quartz cells can be used for thousands of hours without devitrification if precautions are taken to ensure that the outside surface is scrupulously clean before raising them to temperature. Any surface dirt, a water spot or a single fingerprint is a potential seed for devitrification." 208.42.18.222
I added a paragraph to this section, which I'll quote in its entirety here: "It should be pointed out that virtually all of the energy from light bulbs of any type is converted into heat. During cold months when a building is being heated, the heat produced by a light bulb is helping to heat the building, and this needs to be taken into account when calculating the energy cost of different types of bulbs. In a typical home using electric heat, for example, light bulbs of any type do not produce any electricity cost during cold months, since the heat produced by the bulbs simply offsets heat that would have been produced by the home's heating system."
Every discussion I've ever seen on the cost of using different types of bulbs always completely ignores the fact that light bulbs do not "use up" any electricity whatsoever, they simply turn it into heat. If the bulb is in a building which needs to be heated, as is true much of the time, then the inefficient old incandescent bulbs can be every bit as efficient as the fluorescent or LED bulbs, since the heat being produced by the bulbs is helping to heat the building. -- Xyzzyplugh 13:04, 24 June 2006 (UTC)
Well, I don't know about you, but using electricity for heating would not be my first choice. Since you usually have to burn something (coal for most of the country) for the electricity, then you are already at 40% efficiency for heating. Using natural gas or heating oil is about 90-98% efficient. If not wasting the heat, then you are wasting you're money. And here in NC, heating costs far less than A/C in sticky summers, so not only is the heat wasted, it would make my A/C work that much harder. -- mjtimber 18:25, 13 October 2006 (UTC)
Does the "Operation removes lightbulb from anus" news link (added with this edit: http://en.wikipedia.org/?title=Incandescent_light_bulb&diff=61329116&oldid=61100085) have any place in the External Links section in this article? I think not, but I thought I should ask before removing it. It seems the point of the linked story is that the guy somehow ended up with an object in his anus, and the fact that that object was a light bulb isn't terribly significant. I think the link adds no value to this article and therefore should be removed. Ra* 23:36, 14 August 2006 (UTC)
Hard to believe you can get sunburn from halogen UV - I'd say it's the heat, not the UV that burns your skin. I added the {{fact}} template, a reference would be nice if this is indeed true. Sure, filtered halogens are used as UV sources (e.g. a dentist's filler hardening light), but the percentage of UV is so small that normally, the glass in front of a halogen is for explosion, not UV protection. (Maybe the writer here confuses halogen with HMI lamps - they produce copious amounts of UV!)-- Janke | Talk 10:03, 1 October 2006 (UTC)
I heard somewhere that the New York Subway used light bulbs with a thread that is a left-handed helix instead of the standard right-handed helix, to discourage people from stealing them and using them. Does anyone have a good reference for this factoid? Perhaps it could be mentioned in the article. Itub 21:14, 2 October 2006 (UTC)
I've been trying to find out the difference between CA, C7, and C9 bulbs. One, or all of them, is the Candlabra kind, but I don't know the difference. These terms may be used in the U.S. only.
Do you think that the redirects at the top of the pages are maybe a bit too confusing? You know you can follow 'incandescent light bulb' to 'lamp (electrical component) to 'light fixture', then to 'stage lighting instrument' And these are all quite substantial articles. I think a disambiguation-type page would make things a lot easier to navigate... Theonlyduffman 07:19, 7 November 2006 (UTC)
This article seems to me pretty lacking when it comes to the physics of incandescence..
all it says is: 'An electric current passes through a thin filament, heating it and causing it to emit light.' It really should go more in depth about the thermal motion of electrons and the fact that they the acceleration of electrons results in emission of EMR. But I'm not the one to write about it as I've only learnt this stuff in my year 12 physics course this year.
Its rather important though... the fundamental aspect of how it functions, which sets it apart from UV lamps, etc.
The german version of the article claims that the following statement about halogen lamps is a common myth: "A tungsten-halogen lamp creates an equilibrium reaction in which the tungsten that evaporates when giving off light is preferentially re-deposited at the hot-spots, preventing the early failure of the lamp." It claims that it is actually preferably deposited at colder spots, and the prolonged liftetime of a halogen lamps is mostly because of their higher pressure. —The preceding unsigned comment was added by 84.173.241.50 ( talk) 18:37, 5 December 2006 (UTC).
Jobrien13057 added chlorine to the list of halogens used in tungsten-halogen lamps. I've reverted that out for now, but I'm more than willing to be proven wrong with a citation. Anyone have one?
Atlant 16:52, 14 December 2006 (UTC)
It the beginning of the article, it says: The current heats the filament to an extremely high temperature (typically 2000 to 6000 K depending on the filament type, shape, and amount of current passed through).
But I'm inclined to doubt this information, as tungsten melts at 3422K, and boils at 5555K, making me think that the filament is never "typically" heated to such a high temperature.
—The preceding unsigned comment was added by 24.147.72.202 ( talk • contribs).
I forget the names myself, but could someone add that to the history.
—The preceding unsigned comment was added by 70.48.39.164 ( talk) 02:53, 4 January 2007 (UTC).
It appears that John William Starr had the first American patent for his carbon-filament incandescent light bulb, but I can't seem to find much other information about him. —The preceding unsigned comment was added by Monstrosity ( talk • contribs) 07:39, 12 January 2007 (UTC).
Many links to www.pegasusassociates.com on other articles were link spam. After removing a link to www.pegasusassociates.com on this article, I wasn't so sure it was link spam, so I reverted my link removal. I'll watch what others do and follow their lead. 24.160.188.24 22:45, 26 January 2007 (UTC)
Is there truth to the rumor that the light from incandescent light bulbs is more comfortable and less damaging to the health of human eyes, than is the light from fluorescent light bulbs? White collar workers who work daily under the light of fluorescent light bulbs report more eye strain? Are the increased medical costs and anguish worth the decrease in greenhouse emissions here? 192.31.106.34 17:18, 20 February 2007 (UTC)
I was looking around at other websites (namely http://www.thehistoryof.net/the-history-of-the-light-bulb.html and http://invsee.asu.edu/Modules/lightbulb/meathist.htm) that claim Warren De la Rue enclosed the platinum filament in the year 1820 rather than 1840 as the article says. Is Wiki wrong? Throktar 05:49, 27 February 2007 (UTC)Throktar
Warren de la Rue must have been something of a child prodigy, because he was born in 1815 and was only 5 years old in 1820. 1840 is the year you're looking for, guys. - Rob Carter -
Yes I noticed this too. But I was unsure if it was even the same person. When I read through Warren de la rue's page, I saw only things about achievements in Astronomy and nothing about the light bulb. I still havn't found a source that says 1840 as the date either. User:Throktar
The section on the halogen lamp should be its own article. There is already a page with that name created in 2002 as a redirect.
This would trim this lengthy article, improving readability and ease of use. A lot of relevant information from this article could also be transcribed over, creating more relevant article for those looking for information on halogen lamps.
Ng.j 15:28, 4 March 2007 (UTC)
Halogen contain bromine and iodine and other halogens not a vacuum in a regular incandescent bulb
Halogen are generally sold specifically as halogen, and function differently than regular incandescents. They are also banned many places where normal incandescents are not (for example, most college dormitories) 67.94.175.114 20:54, 15 June 2007 (UTC)
Hey - this is my first post, so be gentle on me. I'm not quite sute how all this works. All I wanted to say was that Australia has not banned the incandescent light globe as stated in the introduction to the article. EJH69 07:38, 22 March 2007 (UTC)
Someone recently removed the brackets [ ] from the the convenience links to online sources. The practice I am familiar with is to put the brackets around the html link and then to have text outside the brackets identifying the source. With this, the weblink, which may be quite long, appears in the reference section as a colored number, and the verbal description appears as black text. Is there a convention to just have the weblink and the description of it between the <ref> and </ref> in the inline cite in the text? I reverted to the previous version pending discussion. Edison 23:54, 12 March 2007 (UTC)
It is a shame that lighting efficiency is such a complex technical subject! It seems like the one thing people could most clearly agree on and understand is what percent of the energy supply turns directly into heat, so these numbers should be listed. But what ordinary folk most want to know is, what percent of the energy supply is emitted in the visible spectrum, from the light fixture as a whole. The complexities of adjusting that number to compensate for the sensitivity of the eye to various frequencies leads to numbers that should certainly be mentioned, but not as the only or even primary numbers here. (If a black box turns all of the electricity supplied into emitted orange light, to me that is 100% efficient. If another box turns all of the electricity supplied into emitted purple light, to me that is 100% efficient. If a scientist considers one to be more "efficient" than the other, because the eye sees purple better or worse than orange, that would be interesting to know, but would not change the fact that each is basically 100% efficient.)- 69.87.193.242 15:31, 4 April 2007 (UTC)
Incandescent bulbs have a low resistance when cold, about one-tenth of the hot resistance. So, when they are turned on, they use about ten times as much power for an instant, until the filiment gets hot.- 69.87.193.242 15:31, 4 April 2007 (UTC)
Often, when an incandescent bulb is at the end of its life, it will keep working if left on and not disturbed. But after being turned off and cooling down, it will then fail immediately (sometimes with a flash) when turned on, due to the stresses of thermal shock and various changes caused by power cycling.- 69.87.193.242 15:31, 4 April 2007 (UTC)
You could take a short sequence with the correct exposure of filament off, then adjust to the correct exposure for filament on" and power it up. It would also be possible to illuminate the filament with another source (like a slide projector) and focus the light on the filament in the "dark" frames to reduce the brightness change. Some incandescent bulbs "sing" at a high frequence when on. The support locations probably help define the frequency. Edison 23:07, 10 April 2007 (UTC)
Has anyone any solid proof that incandescent bulbs have been banned anywhere in the world at all? The existing section lacks such evidence, and only talks about proposals and possibilites. Should the whole section be deleted or re-written? I think most if not all the proposals are political spin, and quite unreal. There are rumours that one CFL maker (Phillps in Holland) is trying to push politicians in europe to ban the bulb (!) so that it can reap vast profits from its CFL arm. Peterlewis 14:51, 6 April 2007 (UTC)
Those alleged plans are simply spin and political hype. I have seen no substantial and well based government reports at all. All the current refs in the article are newspaper reports or based on environmental sites which have an agenda to pursue. Any government sites have very limited advice. Wki should try to keep a neutral base for its articles, and not simply push a political agenda. Peterlewis 12:41, 11 April 2007 (UTC)
It depends how you define efficiency. 100% of the electricity coming into my home for lighting ends up as useful energy. If you widen the system to include the power station, you will find that some power stations use the waste heat for space heating elsewhere. The Scandinavians and Russians are very good at using waste heat in CHP systems.
Peterlewis
16:16, 11 April 2007 (UTC)
I know it to be a fact that Germany after 1933 propagated the view that Jews could not be trusted. Are you seriously expecting Wiki to air such view (if Wiki existed in the 1930s)? You must be very naive if you expect citizens to believe what their governments tell them. Why should Wiki act as their mouthpiece? Wiki must stand by verifiable facts and not hide behind government statements or websites. If you must put your own POV, then you have to accept that others have a different viewpoint, and that their views need representation. Peterlewis 19:05, 11 April 2007 (UTC)
Why is much of the introduction to this page on Incandescent light bulbs talking about CFLs?
I realise they are mentioned in relation to proposed laws in a handful of jurisdictions to ban incandescent lights, but surely there info that is more relevant that should be placed there. Most of the last paragraph sounds to me like little more than an attack piece against those proposed laws than anything relevant to a factual article. Canderra 16:48, 30 April 2007 (UTC)
"Higher wattage bulbs tend to be more efficient than lower wattage ones. One reason for this is the fact that thicker filaments can be operated at a higher temperature, which is better for radiating visible light. Another reason is that since higher wattage bulbs would lead you to use fewer bulbs, you buy fewer bulbs and the cost of bulbs becomes less important. To optimize cost effectiveness in this case, the filaments are designed to run hotter to improve energy efficiency to reduce your electricity costs. Smaller bulbs use less electricity apiece, making the cost of the bulb more important. This is why lower wattage bulbs are often designed to last 1500 to a few thousand hours instead of 750 to 1000 hours. Designing the bulbs to last longer reduces their light output and energy efficiency." [19]
Please add lumens/watts for typical 4W/7W E12 candelabra nightlight bulbs. Explain why lower wattage bulbs are so much less efficient. Add good links to collections of real spec sheets...- 69.87.204.2 20:42, 15 May 2007 (UTC)
There is a lot of content about halogen lamps - looks like it could be spun out to get this article down in size and not so rambling in content. -- Wtshymanski 23:37, 18 May 2007 (UTC)
Are the output etc statistics given (and that appear on the labels in the stores) for a new bulb, or typical averages over the service life? Over the service life, how does the output (lumens) and efficiency (lumens per watt) vary, for ordinary 40-100W 120VAC bulbs? It seems like as the filament evaporates, the bulb would become more like a lower-wattage bulb, and have higher resistance, emit less light, and be less efficient in lm/W -- is this correct? How large is the typical change? Where is there more data about this? Eventually, if we want to compare different lighting technologies fairly, we need to be discussing typical average performance of the life of the device/product/system, not just "maximum when new" claims.- 69.87.201.16 11:20, 25 May 2007 (UTC)
"The average light output of a lamp over its rated life. Based on the shape of the lumen depreciation curve, for fluorescent and metal halide lamps, mean lumens are measured at 40% of rated lamp life. For mercury, high-pressure sodium and incandescent lamps, mean lumen ratings refer to lumens at 50% of rated lamp life (See Lumen Maintenance)."
"A measure of how well a lamp maintains its light output over time. It may be expressed numerically or as a graph of light output vs. time."
[20]- 69.87.199.232 13:17, 19 June 2007 (UTC)
(there are said to be about five billion light bulb sockets in North American households -- if we can pin down and source some such statistic, it should maybe be in the intro)
We need some photos of prism-separation of incandescent light.
These are interesting resources:
- 69.87.203.221 02:04, 26 May 2007 (UTC)
Yellowish-white light emitted in all directions. Available in either clear or frosted. Types: General (A), Globe (G), Decorative (D) (flame, teardrop and other shapes)
Reflective coating inside the bulb directs light forward. Flood types (FL) spread light. Spot types (SP) concentrate the light. Reflector (R) bulbs put approximately double the amount of light (foot-candles) on the front central area as General Service (A) of same wattage.
Parabolic Aluminized Reflector (PAR) bulbs control light more precisely. They produce about four times the concentrated light of General Service (A), and are used in recessed and track lighting. Weatherproof casings are available for outdoor spot and flood fixtures. 120V (PAR) 16, 20, 30 and 38 bulbs: Available in numerous spot and flood beam spreads. Like all light bulbs, the number represents the diameter of the bulb in 1/8s of an inch. Therefore, a PAR 16 is 2" in diameter, a PAR 20 is 2.5" in diameter, and a PAR 38 is 4.75" in diameter.
-- Halogen Bulbs are available in two distinct voltage types - 120V AC and 12V AC/DC. 12V MR16 and MR11 bulbs are available in multiple color temperatures.
Types of Bulbs and Their Usage
"HIR" means that the bulb has a special coating that reflects infrared back onto the filament. Therefore, less heat escapes, so the filament burns hotter and more efficiently. [21]
[22] - 69.87.199.232 13:42, 19 June 2007 (UTC)
I hope nobody objects to the reversion of the following line "During WWII, Hitler liked to burn jews and use their ashes to reduce oil usage." from 209.129.155.253 of the California State University Network. Kesmet 21:33, 20 July 2007 (UTC)
Nobody would object except perhaps 209.129.155.253. Revert this sort of stuff quickly, freely and without prejudice. And don't bother entering a Talk page item. Just do it! Jim77742 11:01, 6 September 2007 (UTC)
I reverted an edit which removed a reference which stated that Edison's was the first "practical" light bulb. Let's discuss what constitites an incandescent electric light, and what factors make one practical or not. The determination is not really up to an editor; it should be cited to reliable sources who say a bulb was or was not a practical incandescent light. As soon as the battery was invented, around 1800, experimenters noted that electric current of sufficient amperage would make metals such as platinum (favored for its high melting point) and the nonmetal carbon glow brightly. The arc light was demonstrated by Davy before 1810. When the thin carbon rods of the arc light were touched together to start the arc, they glowed brightly: they became literally incandescent before they were drawn apart and the aarc light was exhibited. If the conductor glowed brightly, it soon burned out, so it was a nice demo for a science class or to show a newspaper reporter, but not yet a practical light. A reporter could be impressed by a wire glowing red, but it would not be a satisfactory or practical light. If there were any oxygen left in the enclosure, it would soon burn out, and in any event the carbon from the heated rod would soon darken the glass. I say "rod" because generally early experimenters gave no thought to the need for a high resistance carbon filament, to allow powering a light from a central generating plant. They just connected a huge and expensive battery to a nearby conductor, made it glow for a few minutes, and voila. No one stood watching the demo 24 hours a day to notice that the glowing conductor only lasted perhaps one evening, like a candle wick made of platinum. Getting a patent on an incandescent electric light in the 1840's or 1850's does not constitute reducing the idea to practice. Swan and Edison in the late 1870's were the first to create incandescent lights that had any degree of practicality, as opposed to replicating the demonstration from the beginning of the 19th century that electric current makes a conductor glow for a while, until you increase the current to get near-white incandescence, soon after which it would burn out. Swan and Edison both have claims to fame in the development, but Edison accomplished a better product sooner, partly because of his greater research budget. See above under "Warren De la Rue's date is wrong?" for more references countering claims that earlier experimenters were the "true inventors." It is hard to document accomplishments of De la Rue because sometimes sources say De la Rive. Both experimented with electricity. Several experimenters were brought forward in patent litigation of the 1890's to make hard to substantiate claims of prior research (just as happened with the telephone). Edison 22:38, 5 September 2007 (UTC)
Whew. I've tried to remove some of the excess fuzz and lint from the article. Surprisingly, it only got about 4 kb shorter. I think it's better organized now - comments, please? But three hours at a time is about all I can stand. How long before it needs another clean-up? I really think the "ban the bulb" section should be sput out into a separate article if it needs to be represented at all; it's just a list of press releases at this point. We need more content - how about colored lamps? Rough-service bulbs? So-called long-life bulbs? -- Wtshymanski 16:31, 20 October 2007 (UTC)
Moved contents to Incandescent lamp, since this is the professional term of art for this type of lamp (and it is consistent with the names of other types of lamps). "Bulb" is a colloquial term, like "globe." I didn't know what to do about the discussion, so I left it. Agateller 12:10, 1 November 2007 (UTC)
Note that pages may not be moved by cutting and pasting text from one to another. Pages must be moved with the "move" button. Nontrivial moves must be cleared first through the process described at Wikipedia:Requested moves.-- Srleffler 17:49, 1 November 2007 (UTC)
but modern exit signs must use LEDs)
Fluorescent emergency exit signs are the standard equipment in most of the world.
Most safety codes now require halogen bulbs to be protected by a grid or grille, or by the glass and metal housing of the fixture to prevent ignition of draperies or flammable objects in contact with the lamp.
nope. With just 0.3 of the 6+ billion people on the planet, America is just 5% of the world population. Tabby 14:29, 11 November 2007 (UTC)
I believe that there should be a link under the title along the lines of "Lightbulb redirects here. For Fluorescent bulb, click here. -- HobbesDS ( talk) 02:09, 7 January 2009 (UTC)