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I'm doing a presentation at UT Austin in a couple of weeks - and I'm going to be talking to a bunch of budding computer geeks about color. My mission is to entertainingly undo the mess that people are usually taught on the subject of color. All the wierd stuff we talk about here all the time basically. It's called "How to successfully argue that black is white, magenta is a shade of green and yellow probably isn't yellow". Anyway, one thing I want to do is to split some white light into a spectrum using first an incandescent lamp and then a white LED flashlight - and I'm hoping to get a relatively smooth rainbow out of the incandescent lamp flashlight and some nice, narrow red, green and blue lines out of a white multi-LED flashlight. I don't YET have a prism - that's on order (gotta LOVE the Internet!). But I won't have a lot of time between it arriving and needing to do the talk - so experimentation needs to be minimized. Hence I have a few questions of an 'optical' nature...
Any ideas?
SteveBaker ( talk) 00:23, 5 February 2009 (UTC)
1. Two slits was the way it used to be done - problem - you lose >99% of the light - so make sure the lecture room has curtains (most have?) and suggest getting a low light video camera to capture the small image - then project it using a DLP onto the big screen.
2. Use the dvd/cd as diffraction grating (again in a darkened room) - this does work (so persevere) - I can see quite clearly what the energy saving light bulb I'm using is made up of using this method - you need to look off the axis of the main reflection...
3. dunno - maybe the silver foil and cylinder trick above may help. NOTE that the circular disc at the end of the prism will act as a 'point source' of light with diameter (blurry-ness) similar to the diameter of the disc - therfore placing a lens with the disc at the focal length of the lens should produce a roughly parallel beam. (thin cylinders and short focal length lens help here to reduce the width of the beam.)
4. as a rusty chemist the answer is almost certainly (probably) see Chemiluminescence - the article suggests that often the reaction (when you break the stick mixing the chemicals) produces uv light, and a sensitiser (uv fluorescence) makes the coloured light - the fluorescents can be expected to be likely to be monochromatic - but not as narrow a range of frequencies as the sodium d-line - ie a braod peak. 87.102.126.244 ( talk) 00:58, 5 February 2009 (UTC)
In the days of Newton, experiments requiring monochromatic light passed sunlight through stained glass windows, which apparently produces sufficiently bright and monochromatic light to see first order diffraction lines in simple setups. I don't know how true this is across different colors, or if the stuff that's sold today transmits as narrow a spectrum as the old stuff, but it's pretty cheap to buy in small amounts. Someguy1221 ( talk) 08:56, 5 February 2009 (UTC)
Incidentally, Steve, if you're looking for a quick-and-dirty "colour is in the eye of the beholder" demonstration, I doubt anything is simpler than showing the CCD in your cameraphone can see the the flashing IR LED in a tv remote control where the eye can't (I think that should also be true of a UV source, although I can't immediately think of a household UV source). 87.113.74.22 ( talk) 15:33, 5 February 2009 (UTC)
Looking at locations of sinkholes in the pennines I notice that many occur in lines close together on contour lines (eg~same height) - as I think that sinkholes are made by collapse of underground caverns caused by erosion of the limestone bedrock this seems wrong - I would expect the sinkholes to go downhill, or occur in a fashion unrelated to the overlying height map.
Can someone explain what is going on. Thanks. 87.102.126.244 ( talk) 00:48, 5 February 2009 (UTC)
Update - they seem to often occur between the boundary of the river valley (flattish) and the hills surrounding. Would OS coordinates help?
It's possible that I need a basic lesson in geology - are the sinkholes formed by surface water running off through cracks or flaws already existing in the limestone - or are they due to underground collapse.? Also are they new (ie made after glaciation) or old (uncovered by glacial activity).? Does/do flaws in the underlying millstone grit have something to do with it - such as cracks or step formations.? Is the process well understood. (I'm refering to sinkholes in the pennines - around Howgill fells in particular) Thanks/ Here's an example- (shake holes) http://www.multimap.com/s/dWF6DVqH —Preceding unsigned comment added by 87.102.126.244 ( talk) 17:47, 5 February 2009 (UTC)
HOW DOES THE NUMBER OF NEURONS IN THE BRAIN INCREASE? WHAT IF WE USE OUR BRAIN MORE EFFECTIVELY OR MUCH MORE CONCERN THE QUANTITY OF NEURON? —Preceding unsigned comment added by Mustekke6184 ( talk • contribs) 02:52, 5 February 2009 (UTC)
I'm working on some Chemistry homework and for one problem I have to calculate the molality of concentrated Sulfuric acid. The information I am given is the density: 1.84 g/mL and the mass percent of solute: 95%.
I assume for calculation's sake that I have 1000g of solution. Because of the mass percent, I should have 950g of H2SO4 and 50g of water. Thus from that I calculate the moles of solute to be 9.69 mols. Since the density of water is 1 g/mL, I calculate I have .050L of water. Thus the molality is calculated as 9.69mols solute /.050L of solvent = 194 mols/kg. Is this correct? It seems like a ridiculously high number to me compared to those in the other examples. Have I done something wrong? I guess what I'm also having trouble wrapping my head around is dissolving nearly a kilogram of H2SO4 in only 50 mL of water. According to the density, my total solution volume should be 543.5 mL. I feel like I have misstepped somewhere but I cannot figure it out.
Help is appreciated 198.82.110.57 ( talk) 03:13, 5 February 2009 (UTC)
Hey, I'm doing some research and I'd like some help finding the articles I'd need! I'd like to know...What ingredients in the liquids (orange juice, Coke, Red Bull, milk, salt water) are considered "chemicals"? For example...salt water has salt; milk has calcium. —Preceding unsigned comment added by 69.178.20.243 ( talk) 04:51, 5 February 2009 (UTC)
The second half of A Study in Scarlet (the first appearance of Sherlock Holmes) takes place primarily in the western USA, beginning in a region (consisting essentially of the Four Corners states, Wyoming, and Nevada) that Conan Doyle describes as extremely desolate (it's a bit fictionalised). This region he names the "great alkali plain" (read the relevant part of the story here), a description that confuses me. Why "alkali"? It's not as if the region was composed solely of francium, lithium, and the elements in between, and there's nothing in the story that suggests that it would have a strongly basic pH. Any ideas what this might mean? Nyttend ( talk) 05:52, 5 February 2009 (UTC)
A related question to my last one.
How does the membership of AAAS compare to FRS(Ramanathan) —Preceding unsigned comment added by 212.247.70.129 ( talk) 07:58, 5 February 2009 (UTC)
I do not think that is entirely accurate!If you look through the membership of the Royal Society you find people like Samuel Pepys and Robert Darwin to quote two!People who have nothing to do with science have been members throughout the history of the Society eg.Lord Brougham,John Locke in the past!Even when you look at the membership in the last 50 years people like Margaret Thatcher who despite having studied chemistry is no scientist!What about Quentin Hailsham,a lawyer!And the present list has Partha Dasgupta,an economist!
AAAS has always been open that it recognises excellence in all human endeavours.And US has 4-5 times the population of UK!Therefore the size of the membership is roughly commensurate. The reason I felt AAAS membership would be propbably more prestigious internationally is: 1.Royal Society bars people from becoming fellows unless you are a Commonwealth or an Irish citizen(Foreign Membership apart which is very rare in any case!).Besides the by laws as on the site state that if you hold a second nationality other than Commonwealth or Irish you are automatically debarred from becoming a member(except a Foreign Member).
2.As far as I know AAAS has more Nobel Laureates on its rolls than any other learned society in the world in all disciplines.
I would like the researchers to correct me if I am wrong.(Ramanathan)
'To my inexperinced eye,AAAS has 171 Nobel laureates and Royal Society has 8.I also counted the Nobels in science for AAAS-118!That surely would make it the most prestigious learned society!(Ramanathan)'
If we can't really be sure that the laws of physics are the same in our own universe, don't even know if parallel universes exist, how can we say that they are inaccessible? Seems to me like an awfully arrogant statement considering our current level of ignorance. Bastard Soap ( talk) 08:52, 5 February 2009 (UTC)
To quote Donald Rusmfeld...There are known knowns, there are things we know that we know. There are known unknowns. That is to say, there are things we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know.
It doesn't seem like ignorance to me - it is making statements/theories based on the best available knowledge, and then being prepared to revise those as further information becomes available. 194.221.133.226 ( talk) —Preceding undated comment was added at 10:04, 5 February 2009 (UTC).
I think I would define universe as the place where our physical constants hold true, even though I think it's trivial what we do call our little bubble. So do we have any real reason to assume they would be inaccessible except semantics? Bastard Soap ( talk) 18:54, 5 February 2009 (UTC)
Moved question to the Language Desk. -- Milkbreath ( talk) 11:31, 5 February 2009 (UTC)
In Cork taint:
Does polyethylene remove other good aromatic chemicals as well? How does polyethylene absorb 2,4,6-trichloroanisole? The chlorine? -- Toytoy ( talk) 11:51, 5 February 2009 (UTC)
Ever since I was young I used to look at bulbs, and by moving my eyes in different directions I could form letters and even words using the bulb as a pen.
For example if you look at a bulb and move your eyes down, that would 'move' the bulb 'up', forming a stroke. Looking left moves the bulb right. Closing your eyes allows you to move the 'pointer'.
I've never encountered anybody else that ever does this. Do you have any references or anecdotes about this? Perhaps I can control my eye ball muscles in a very controlled way.
Rfwoolf (
talk)
12:15, 5 February 2009 (UTC)
I learned the hard fact that some wines are so bad that you don't even use them for cooking while I was in college. If properly aging for years or decades may improve the tastes of good wines, can the taste of a regular cooking wine, when "cooked" with aeration and under low heat separately from the food, be improved?
Is it possible to improve the taste of a large batch of cheap wine by hiring a chemical expert and "cook" the wine strategically (e.g, aeration, heating, adding sugar, adding so-called " liquid smoke", removal of unpleasant sulfur compounds) so its final chemical profile may match a much better wine that has been aged?
Is it possible to salvage over-aged wine by blending in young wine? -- Toytoy ( talk) 12:37, 5 February 2009 (UTC)
can someone explain how einstein got this formula? the wikipedia article doesn't explain how he got this thing please explain that also. And the article says that he omitted the second term just because he wanted that. How can he do so without changing the value of the equation?-- Harnithish ( talk) 15:54, 5 February 2009 (UTC)
Why is it that certain groups of people believe that water flouridation is a conspiracy to keep the hoi poloui stupid? Is there any particular reason for this belief? What is its origin and who first proposed it? Why is it not taken seriously by the scientific community or society at large? 86.132.243.243 ( talk) 17:11, 5 February 2009 (UTC)
If all plants went extinct, could animals continue to live? When would carnivorous species start to go extinct? 86.8.176.85 ( talk) 18:50, 5 February 2009 (UTC)
If stuff like kelp isn't classified as a plant, then I guess it doesn't fall under the criteria of my question (although I did think it was one). I asked about carnivores because I figured they'd be able to eat each other for a awhile at least. What sort of life would start filling the gap left by plants? What would happen to the atmosphere? Or would pretty much all interesting life be doomed (above ground, anyway)? Your answers are fascinating, thanks. 86.8.176.85 ( talk) 20:59, 5 February 2009 (UTC)
I remember seeing an experiment years ago where you place an egg over a candle flame until the suit collects upon it, then you place it in a glass of water and it produces a shiny, silver effect. Is this just air bubbles accululating on the egg, producing a shiny effect, or is there something else going on? — Cyclonenim ( talk · contribs · email) 20:27, 5 February 2009 (UTC)
The wonderful Tim Minchin, in his beat poem Storm, has the line:
Water has memory!
And whilst its memory
Of a long lost drop of onion juice is infinite,
It somehow forgets all the poo it's had in it.
How do homeopaths explain this? Of all the impurities and previous things the water cycle has had in it? -- MacAddct1984 ( talk • contribs) 21:24, 5 February 2009 (UTC)
Science desk | ||
---|---|---|
< February 4 | << Jan | February | Mar >> | February 6 > |
Welcome to the Wikipedia Science Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
I'm doing a presentation at UT Austin in a couple of weeks - and I'm going to be talking to a bunch of budding computer geeks about color. My mission is to entertainingly undo the mess that people are usually taught on the subject of color. All the wierd stuff we talk about here all the time basically. It's called "How to successfully argue that black is white, magenta is a shade of green and yellow probably isn't yellow". Anyway, one thing I want to do is to split some white light into a spectrum using first an incandescent lamp and then a white LED flashlight - and I'm hoping to get a relatively smooth rainbow out of the incandescent lamp flashlight and some nice, narrow red, green and blue lines out of a white multi-LED flashlight. I don't YET have a prism - that's on order (gotta LOVE the Internet!). But I won't have a lot of time between it arriving and needing to do the talk - so experimentation needs to be minimized. Hence I have a few questions of an 'optical' nature...
Any ideas?
SteveBaker ( talk) 00:23, 5 February 2009 (UTC)
1. Two slits was the way it used to be done - problem - you lose >99% of the light - so make sure the lecture room has curtains (most have?) and suggest getting a low light video camera to capture the small image - then project it using a DLP onto the big screen.
2. Use the dvd/cd as diffraction grating (again in a darkened room) - this does work (so persevere) - I can see quite clearly what the energy saving light bulb I'm using is made up of using this method - you need to look off the axis of the main reflection...
3. dunno - maybe the silver foil and cylinder trick above may help. NOTE that the circular disc at the end of the prism will act as a 'point source' of light with diameter (blurry-ness) similar to the diameter of the disc - therfore placing a lens with the disc at the focal length of the lens should produce a roughly parallel beam. (thin cylinders and short focal length lens help here to reduce the width of the beam.)
4. as a rusty chemist the answer is almost certainly (probably) see Chemiluminescence - the article suggests that often the reaction (when you break the stick mixing the chemicals) produces uv light, and a sensitiser (uv fluorescence) makes the coloured light - the fluorescents can be expected to be likely to be monochromatic - but not as narrow a range of frequencies as the sodium d-line - ie a braod peak. 87.102.126.244 ( talk) 00:58, 5 February 2009 (UTC)
In the days of Newton, experiments requiring monochromatic light passed sunlight through stained glass windows, which apparently produces sufficiently bright and monochromatic light to see first order diffraction lines in simple setups. I don't know how true this is across different colors, or if the stuff that's sold today transmits as narrow a spectrum as the old stuff, but it's pretty cheap to buy in small amounts. Someguy1221 ( talk) 08:56, 5 February 2009 (UTC)
Incidentally, Steve, if you're looking for a quick-and-dirty "colour is in the eye of the beholder" demonstration, I doubt anything is simpler than showing the CCD in your cameraphone can see the the flashing IR LED in a tv remote control where the eye can't (I think that should also be true of a UV source, although I can't immediately think of a household UV source). 87.113.74.22 ( talk) 15:33, 5 February 2009 (UTC)
Looking at locations of sinkholes in the pennines I notice that many occur in lines close together on contour lines (eg~same height) - as I think that sinkholes are made by collapse of underground caverns caused by erosion of the limestone bedrock this seems wrong - I would expect the sinkholes to go downhill, or occur in a fashion unrelated to the overlying height map.
Can someone explain what is going on. Thanks. 87.102.126.244 ( talk) 00:48, 5 February 2009 (UTC)
Update - they seem to often occur between the boundary of the river valley (flattish) and the hills surrounding. Would OS coordinates help?
It's possible that I need a basic lesson in geology - are the sinkholes formed by surface water running off through cracks or flaws already existing in the limestone - or are they due to underground collapse.? Also are they new (ie made after glaciation) or old (uncovered by glacial activity).? Does/do flaws in the underlying millstone grit have something to do with it - such as cracks or step formations.? Is the process well understood. (I'm refering to sinkholes in the pennines - around Howgill fells in particular) Thanks/ Here's an example- (shake holes) http://www.multimap.com/s/dWF6DVqH —Preceding unsigned comment added by 87.102.126.244 ( talk) 17:47, 5 February 2009 (UTC)
HOW DOES THE NUMBER OF NEURONS IN THE BRAIN INCREASE? WHAT IF WE USE OUR BRAIN MORE EFFECTIVELY OR MUCH MORE CONCERN THE QUANTITY OF NEURON? —Preceding unsigned comment added by Mustekke6184 ( talk • contribs) 02:52, 5 February 2009 (UTC)
I'm working on some Chemistry homework and for one problem I have to calculate the molality of concentrated Sulfuric acid. The information I am given is the density: 1.84 g/mL and the mass percent of solute: 95%.
I assume for calculation's sake that I have 1000g of solution. Because of the mass percent, I should have 950g of H2SO4 and 50g of water. Thus from that I calculate the moles of solute to be 9.69 mols. Since the density of water is 1 g/mL, I calculate I have .050L of water. Thus the molality is calculated as 9.69mols solute /.050L of solvent = 194 mols/kg. Is this correct? It seems like a ridiculously high number to me compared to those in the other examples. Have I done something wrong? I guess what I'm also having trouble wrapping my head around is dissolving nearly a kilogram of H2SO4 in only 50 mL of water. According to the density, my total solution volume should be 543.5 mL. I feel like I have misstepped somewhere but I cannot figure it out.
Help is appreciated 198.82.110.57 ( talk) 03:13, 5 February 2009 (UTC)
Hey, I'm doing some research and I'd like some help finding the articles I'd need! I'd like to know...What ingredients in the liquids (orange juice, Coke, Red Bull, milk, salt water) are considered "chemicals"? For example...salt water has salt; milk has calcium. —Preceding unsigned comment added by 69.178.20.243 ( talk) 04:51, 5 February 2009 (UTC)
The second half of A Study in Scarlet (the first appearance of Sherlock Holmes) takes place primarily in the western USA, beginning in a region (consisting essentially of the Four Corners states, Wyoming, and Nevada) that Conan Doyle describes as extremely desolate (it's a bit fictionalised). This region he names the "great alkali plain" (read the relevant part of the story here), a description that confuses me. Why "alkali"? It's not as if the region was composed solely of francium, lithium, and the elements in between, and there's nothing in the story that suggests that it would have a strongly basic pH. Any ideas what this might mean? Nyttend ( talk) 05:52, 5 February 2009 (UTC)
A related question to my last one.
How does the membership of AAAS compare to FRS(Ramanathan) —Preceding unsigned comment added by 212.247.70.129 ( talk) 07:58, 5 February 2009 (UTC)
I do not think that is entirely accurate!If you look through the membership of the Royal Society you find people like Samuel Pepys and Robert Darwin to quote two!People who have nothing to do with science have been members throughout the history of the Society eg.Lord Brougham,John Locke in the past!Even when you look at the membership in the last 50 years people like Margaret Thatcher who despite having studied chemistry is no scientist!What about Quentin Hailsham,a lawyer!And the present list has Partha Dasgupta,an economist!
AAAS has always been open that it recognises excellence in all human endeavours.And US has 4-5 times the population of UK!Therefore the size of the membership is roughly commensurate. The reason I felt AAAS membership would be propbably more prestigious internationally is: 1.Royal Society bars people from becoming fellows unless you are a Commonwealth or an Irish citizen(Foreign Membership apart which is very rare in any case!).Besides the by laws as on the site state that if you hold a second nationality other than Commonwealth or Irish you are automatically debarred from becoming a member(except a Foreign Member).
2.As far as I know AAAS has more Nobel Laureates on its rolls than any other learned society in the world in all disciplines.
I would like the researchers to correct me if I am wrong.(Ramanathan)
'To my inexperinced eye,AAAS has 171 Nobel laureates and Royal Society has 8.I also counted the Nobels in science for AAAS-118!That surely would make it the most prestigious learned society!(Ramanathan)'
If we can't really be sure that the laws of physics are the same in our own universe, don't even know if parallel universes exist, how can we say that they are inaccessible? Seems to me like an awfully arrogant statement considering our current level of ignorance. Bastard Soap ( talk) 08:52, 5 February 2009 (UTC)
To quote Donald Rusmfeld...There are known knowns, there are things we know that we know. There are known unknowns. That is to say, there are things we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know.
It doesn't seem like ignorance to me - it is making statements/theories based on the best available knowledge, and then being prepared to revise those as further information becomes available. 194.221.133.226 ( talk) —Preceding undated comment was added at 10:04, 5 February 2009 (UTC).
I think I would define universe as the place where our physical constants hold true, even though I think it's trivial what we do call our little bubble. So do we have any real reason to assume they would be inaccessible except semantics? Bastard Soap ( talk) 18:54, 5 February 2009 (UTC)
Moved question to the Language Desk. -- Milkbreath ( talk) 11:31, 5 February 2009 (UTC)
In Cork taint:
Does polyethylene remove other good aromatic chemicals as well? How does polyethylene absorb 2,4,6-trichloroanisole? The chlorine? -- Toytoy ( talk) 11:51, 5 February 2009 (UTC)
Ever since I was young I used to look at bulbs, and by moving my eyes in different directions I could form letters and even words using the bulb as a pen.
For example if you look at a bulb and move your eyes down, that would 'move' the bulb 'up', forming a stroke. Looking left moves the bulb right. Closing your eyes allows you to move the 'pointer'.
I've never encountered anybody else that ever does this. Do you have any references or anecdotes about this? Perhaps I can control my eye ball muscles in a very controlled way.
Rfwoolf (
talk)
12:15, 5 February 2009 (UTC)
I learned the hard fact that some wines are so bad that you don't even use them for cooking while I was in college. If properly aging for years or decades may improve the tastes of good wines, can the taste of a regular cooking wine, when "cooked" with aeration and under low heat separately from the food, be improved?
Is it possible to improve the taste of a large batch of cheap wine by hiring a chemical expert and "cook" the wine strategically (e.g, aeration, heating, adding sugar, adding so-called " liquid smoke", removal of unpleasant sulfur compounds) so its final chemical profile may match a much better wine that has been aged?
Is it possible to salvage over-aged wine by blending in young wine? -- Toytoy ( talk) 12:37, 5 February 2009 (UTC)
can someone explain how einstein got this formula? the wikipedia article doesn't explain how he got this thing please explain that also. And the article says that he omitted the second term just because he wanted that. How can he do so without changing the value of the equation?-- Harnithish ( talk) 15:54, 5 February 2009 (UTC)
Why is it that certain groups of people believe that water flouridation is a conspiracy to keep the hoi poloui stupid? Is there any particular reason for this belief? What is its origin and who first proposed it? Why is it not taken seriously by the scientific community or society at large? 86.132.243.243 ( talk) 17:11, 5 February 2009 (UTC)
If all plants went extinct, could animals continue to live? When would carnivorous species start to go extinct? 86.8.176.85 ( talk) 18:50, 5 February 2009 (UTC)
If stuff like kelp isn't classified as a plant, then I guess it doesn't fall under the criteria of my question (although I did think it was one). I asked about carnivores because I figured they'd be able to eat each other for a awhile at least. What sort of life would start filling the gap left by plants? What would happen to the atmosphere? Or would pretty much all interesting life be doomed (above ground, anyway)? Your answers are fascinating, thanks. 86.8.176.85 ( talk) 20:59, 5 February 2009 (UTC)
I remember seeing an experiment years ago where you place an egg over a candle flame until the suit collects upon it, then you place it in a glass of water and it produces a shiny, silver effect. Is this just air bubbles accululating on the egg, producing a shiny effect, or is there something else going on? — Cyclonenim ( talk · contribs · email) 20:27, 5 February 2009 (UTC)
The wonderful Tim Minchin, in his beat poem Storm, has the line:
Water has memory!
And whilst its memory
Of a long lost drop of onion juice is infinite,
It somehow forgets all the poo it's had in it.
How do homeopaths explain this? Of all the impurities and previous things the water cycle has had in it? -- MacAddct1984 ( talk • contribs) 21:24, 5 February 2009 (UTC)