Saturday, December 12, 2009
Glass and plastic cups
At dinner at a nice but not very nice restaurant the cups could have been either thin light glass or a convincing plastic immitation. To determine which kind they were we tapped the cups with a metal knife. The cups chimed, therefore they were made of glass.
The best guess I have for this is that a glass cup is essentialy one cystal of silicon dioxide whereas a plastic cup is several long chain polymers linked together by strong intermolecular forces. The result is that when force is applied to the glass cup the force translates smoothly through the cup and at the opposite end of the cup the force reverses direction and travels back through the cup. Thus the resonance is the velocity of the comperssion wave through the cup divided by the length. A plastic cup doesn't resonate becuase it's non crystaline structure does not have enough uniformity for the pressure waves to bounce back and forth within it.
- Posted using BlogPress from my iPhone
Tuesday, November 10, 2009
White and Black
A simple idea: paint roofs, roads, and everything else white instead of black. The underlying idea is that the black color absorbs sunlight and converts it to heat energy while white color reflects the light back into space.
Energy Secretary Chu thinks
Does the idea hold up?
The quote from Chu can be misleading. What is the equivalence? The most likely equivalence is that the CO2 emissions from all cars over 11 years will trap some amount of light energy here. That same amount of light energy will be reflected instead of absorbed by painting things white. Also, what roads? All roads everywhere? Or just in the United States?
Two processes will be discussed to help understand this ambitious plan. First the process by which light absorption increases temperature and second the nature of color in terms of absorption and reflection.
Think about a greenhouse in a garden. It's warm. It's warm because ultraviolet and visible light can penetrate the glass and are absorbed by objects inside the greenhouse. Once absorbed, some light energy is converted to heat, making the object warmer, and the rest is emitted as light of a lower wavelength. Light incident as visible and ultraviolet light is converted into infrared light by this process. Infrared light is unable to penetrate glass and so infrared light is trapped inside a greenhouse bouncing from object to object until it is entirely converted to heat energy.
A white object reflects all light and absorbs none. A red object is red because it reflects red light and absorbs other colors of light. A dark object reflects less of the light than it absorbs. A black object reflects no light and absorbs all of it. This is a physical interpretation of light and coupled with the above discussion it is plain to see what significance color has.
Painting surfaces white will reflect light back up into the atmosphere instead of converting it to heat. Much of this light will make it out into space.
The idea is scientifically sound, but practicality issues of course present themselves.
Energy Secretary Chu thinks
"making roads and roofs a paler color would be equivalent to taking all cars worldwide off the road for 11 years."Chu, by the way, won the 1997 Nobel Prize in Physics. Read about it here.
Does the idea hold up?
The quote from Chu can be misleading. What is the equivalence? The most likely equivalence is that the CO2 emissions from all cars over 11 years will trap some amount of light energy here. That same amount of light energy will be reflected instead of absorbed by painting things white. Also, what roads? All roads everywhere? Or just in the United States?
Two processes will be discussed to help understand this ambitious plan. First the process by which light absorption increases temperature and second the nature of color in terms of absorption and reflection.
Think about a greenhouse in a garden. It's warm. It's warm because ultraviolet and visible light can penetrate the glass and are absorbed by objects inside the greenhouse. Once absorbed, some light energy is converted to heat, making the object warmer, and the rest is emitted as light of a lower wavelength. Light incident as visible and ultraviolet light is converted into infrared light by this process. Infrared light is unable to penetrate glass and so infrared light is trapped inside a greenhouse bouncing from object to object until it is entirely converted to heat energy.
A white object reflects all light and absorbs none. A red object is red because it reflects red light and absorbs other colors of light. A dark object reflects less of the light than it absorbs. A black object reflects no light and absorbs all of it. This is a physical interpretation of light and coupled with the above discussion it is plain to see what significance color has.
Painting surfaces white will reflect light back up into the atmosphere instead of converting it to heat. Much of this light will make it out into space.
The idea is scientifically sound, but practicality issues of course present themselves.
Thursday, October 1, 2009
50% chance of rocks, folks.
Short summary: They found an exoplanet (that's a planet orbiting around a different star) that has regular rock precipitation. The day side of the planet is hot enough to vaporize minerals into the atmosphere, and the night side is cool enough to re-form them as mineral rain. Sweet.
http://www.examiner.com/examiner/x-1242-Science-News-Examiner~y2009m10d1-A-planet-that-rocks
http://www.examiner.com/examiner/x-1242-Science-News-Examiner~y2009m10d1-A-planet-that-rocks
Thursday, September 17, 2009
SHArK Abstract/Summary
SHArK (Solar Hydrogen Activity Research Kit) with Pipette Method: Distributed research project examines how electrochemical responsiveness of metal oxides to visible light varies with concentration and droplet size.
The SHArK project is a distributed research project begun at the Univ. of Wyoming. It hopes to find a combination of metal oxides that will absorb visibile light and spilt water with the absorbed energy.
This research explores the potential of Cobalt, Aluminum, and Iron oxides as catalysts for spliting water into O2 and H2 gas using only sunlight. It also explores the effect of varying droplet size and metal nitrate concentration when using the pipette method to prepare test plates for the SHArK project.
A hydrogen-based economy will not be feasible without a more efficient method of producing hydrogen gas. The SHArK project is a distributed research project that engages high school and undergraduate students. In the pipette method metal nitrates in acidic solution are pipetted onto a conducting glass plate and are then baked in an oven at 500 degrees celsius for 24 hours. While in the oven, the metal nitrates oxidize to metal oxides. The plates are then rinsed and placed in a small aquarium-like tank in .1 molar sodium hydroxide solution. An electrode is connected to the plate, a counter electrode is connected to a graphite rod which is submerged in the electrolyte solution. A voltage is applied across these two electrodes. This applied voltage is called the bias. Each plate is usually scanned twice, one with a positive .5 volt bias and once with a negative .5 volt bias. Electronics controlled by a computer measure the current passing through the circut in miliAmps. Electrochemical activity of the metal oxides is examined by analyzing changes in current in the circut. When the detected current increases it is assumed that an n-type metal oxide is donating electrons to the current and thus increasing the current. When the detected current decreases it is assumed that a p-type metal oxide has opened up a hole and electrons have sank into it and thus decreasing the current. A 532 nm (which is actually a frequency-doubled 1064nm CO2 laser IIRC) green laser pointer is used to test the metal oxides for visibile light-induced electrochemistry. The laser is mounted on a LEGO(Registered Trademark) platform and LEGO Mindstorms(R) robotics control two mirrors that reflect the laser beam onto the test plate. The computer software imagines the plate as a grid of 180 collumns and 180 rows for a total of 32,400 individual data points per scan. For each data point, the computer turns on the laser, records the current, turns off the laser, and tells the robotics to move the mirrors to aim the laser at the next point. The robotics move the laser beam like a typewriter; single steps to the right until they reach the end of a row, then a long step back to the left hand edge, and a single step down. The computer ouputs a text file consisting of 32,400 numbers which is then processed using an open source program called imageJ which in turn assigns a color to each value and creates a 180 pixel by 180 pixel image of the scan. Each plate generates two images; one scanned with a positive bias and the other with a negative bias. Because the SHArK project is a distributed research project, it's website is also home to it's results database. Anyone can view the results so far of the project if they create a user account and all researchers can post their results to the main results archive.
The SHArK project is a distributed research project begun at the Univ. of Wyoming. It hopes to find a combination of metal oxides that will absorb visibile light and spilt water with the absorbed energy.
This research explores the potential of Cobalt, Aluminum, and Iron oxides as catalysts for spliting water into O2 and H2 gas using only sunlight. It also explores the effect of varying droplet size and metal nitrate concentration when using the pipette method to prepare test plates for the SHArK project.
A hydrogen-based economy will not be feasible without a more efficient method of producing hydrogen gas. The SHArK project is a distributed research project that engages high school and undergraduate students. In the pipette method metal nitrates in acidic solution are pipetted onto a conducting glass plate and are then baked in an oven at 500 degrees celsius for 24 hours. While in the oven, the metal nitrates oxidize to metal oxides. The plates are then rinsed and placed in a small aquarium-like tank in .1 molar sodium hydroxide solution. An electrode is connected to the plate, a counter electrode is connected to a graphite rod which is submerged in the electrolyte solution. A voltage is applied across these two electrodes. This applied voltage is called the bias. Each plate is usually scanned twice, one with a positive .5 volt bias and once with a negative .5 volt bias. Electronics controlled by a computer measure the current passing through the circut in miliAmps. Electrochemical activity of the metal oxides is examined by analyzing changes in current in the circut. When the detected current increases it is assumed that an n-type metal oxide is donating electrons to the current and thus increasing the current. When the detected current decreases it is assumed that a p-type metal oxide has opened up a hole and electrons have sank into it and thus decreasing the current. A 532 nm (which is actually a frequency-doubled 1064nm CO2 laser IIRC) green laser pointer is used to test the metal oxides for visibile light-induced electrochemistry. The laser is mounted on a LEGO(Registered Trademark) platform and LEGO Mindstorms(R) robotics control two mirrors that reflect the laser beam onto the test plate. The computer software imagines the plate as a grid of 180 collumns and 180 rows for a total of 32,400 individual data points per scan. For each data point, the computer turns on the laser, records the current, turns off the laser, and tells the robotics to move the mirrors to aim the laser at the next point. The robotics move the laser beam like a typewriter; single steps to the right until they reach the end of a row, then a long step back to the left hand edge, and a single step down. The computer ouputs a text file consisting of 32,400 numbers which is then processed using an open source program called imageJ which in turn assigns a color to each value and creates a 180 pixel by 180 pixel image of the scan. Each plate generates two images; one scanned with a positive bias and the other with a negative bias. Because the SHArK project is a distributed research project, it's website is also home to it's results database. Anyone can view the results so far of the project if they create a user account and all researchers can post their results to the main results archive.
Pentacene
Pentacene might be aromatic. It is Five fused benzene rings. And IBM took a sweet picture of it using(I guess) the pauli exclusion principle quantum force. Which doesn't jive with my science learnings. But I do not know all of quantum mechanics, and as soon as I learn how this here buisness was done I will blog about it at length. Until then, it gets a very high "awesome" rating from me. Go IBM. Yay especially for companies funding pure research!
Here is the link.
Pentacene Pics!
Here is the link.
Pentacene Pics!
Elementeo is a sweet Card Game!
A new board game called elementeo is available online for 35 dollars. I expect it to be quite fun for any junior scientists out there. Or some older scientists looking to play like junior scientists. Or some older scientists who are worried junior is reading to much history and not enough science. Or for some older scientists who have a non-scientist significant other and want a fun way to bring them up to speed on science. Party on yall. I want to play this game so if any of you readers get it, please send me some pics and a review of the gameplay.
Tuesday, September 8, 2009
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