Cool! I've never encountered the impact theory. I bought a large number of them ($5, at a post-xmas sale.) The vanes were glass cover-slips, one side soot, the other side white powder (perhaps smoke from burned Mg ribbon?) They had a variety of pressures (and glow differently for the same Tesla coil.) They also have a variety of frictions (spin them mechanically, let them coast down to 60RPM, then count the revolutions until they halt.) With twenty radiometers you can sort them, then keep the best ones (and give the others as xmas gifts.) During evening twilight, with only sunset-glow as illumination, the ones which had the brightest Tesla-coil glow and lowest friction are the ones which spin fastest. Some wouldn't spin at all under those conditions. I've seen versions which appear to have peeled-mica vanes and only one side blackened. Yours in the video looks like soot-and-mica to me. Not metal. (Does the silvery side reflect a red laser as much as aluminum foil does?) I've also seen some apparently using round glass cover-slips. Round microscope-slips are less common, but do exist. All of these are thermal insulators, and since the radiation-cooling is approximately the same for all coated surfaces, no major differences exist between black and white (and so the black side would be greatly heated via visible light, if both surfaces have near-identical cooling.) A metal-vane radiometer with thermally-conductive vanes would be very interesting! If you think you have one with metal vanes, break it open and check by bending the vanes (vent the vacuum, then scratch with a glass-cutter, to avoid imploding the bulb and destroying the vanes.) Or, if to the eye it looks exactly like rough mica, probably that's what it is. These are cheap, $12 each from sciplus if you buy two at a time (glass vanes, diamond shape. Some were mistreated in shipping, and occasionally a corner of a vane is cracked off and missing. Metal foil doesn't shatter like that.) Just now I FINALLY tried laser pointer. Green few-mW laser barely turns the more sensitive ones. But my violet laser 395nM gets it slowly spinning. TEST: aim the violet laser-spot at the center of the vane, observe the motion. Then move the laser-dot closer to the edge, near the upper tip of the diamond-shape (NOT to the outer tip, so no change in leverage.) Yes, it then spins slightly faster, barely noticeable, maybe under 10% faster? Aim at the center again, it visibly slows down (but hard to notice unless watching carefully.) I'll have to set up a laser-holder, rather than doing it by hand. Also, count the revolutions with a stopwatch, to get actual numbers for RPM changes, rather than trying to eyeball it. Put radiometer inside a freezer, and it does go backwards, only to stop after a minute ...then when removed, it slowly spins forward for half a minute. Also, freeze-spray the glass bulb. Or, big slab of dry ice held close. PS, if your radiometer has poor friction, you can bias it with diffuse window-sunlight, just to the threshold where it starts turning extremely slowly. That gets it past the static friction, so a small extra light-source may produce much more obvious results. (Heh, or buy all of them from a museum store, sort for sensitivity, then return the rest back to the store? Or just take a UV flashlight to the store, to open boxes and test RPMs.) ALSO, the glass bearing may have "good spots," and by bouncing the radiometer to reposition the needle, sometimes the sensitivity to light sources will change dramatically.
@EL-bw3xe11 күн бұрын
the electrostatic test is the most important test that says it all
@adnacraigo65905 ай бұрын
Started off my morning right.
@lifeunderthemic5 ай бұрын
It was years since I had asked. Thank you!
@tenlittleindians5 ай бұрын
I've been fascinated by those for decades. I almost bought one on a high school trip to the Chicago museum of Science and Industry in the 70's. I've never bought into their theories as to what made them spin and still don't. I've always wondered if they would spin in space without a glass dome and I suspect that's been tested. I also wonder if it's just a smaller version of our solar system since our earth spins in a semi vacuum too for no apparent reason that makes sense to me. A couple of observations; your light demonstration always directed the energy towards the black surface rather than testing both surfaces in a similar fashion. Your electrostatic demonstration focused on a flow of electrons from the generator poles which were both located on the white vane sides. That experiment in total darkness might prove interesting to see if it causes rotation without any light differences between colors. Your laser is a smaller version of our sun and it gives off heat from it's light which you concentrated on only the black surface. Would a more powerful laser with a color selected that reacts with white more than black and directed only on the white surfaces cause counter rotation? Would a DC high voltage source such as a flyback coil cause the same rotation when presented to one side or the other? Since radio waves can be focused; I wonder if there's been any attempt to build one of these devices with a pair of antennas inside so they could transmit radio waves from one side of the device to the other? They could then switch antennas and transmit in the opposite direction to see if there's any difference. I suspect this has all been tried by first year university students in colleges all around the world decade after decade but I never had the luxury of being one of these students. The curious mind is an animal that's always hungry.
@wbeaty3 ай бұрын
MICROWAVE OVEN! Radio transmitters make these turn very slowly, and the gas glows dim violet. I tried nuking one in the kitchen microwave. The low-pressure gas lights up blinding white, and the vanes instantly spin like a blur. I didn't dare to use full power (the sharp needle tip would just melt.) So, I put an 8cu pyrex cup full of water in there. Rotator-disk removed. Nothing happens. I progressively removed water. Finally, with 4cu water, and a ten-second delay, suddenly the bulb lights up with plasma, and the vanes spin (spinning as usual, with black side retreating.) Afterwards, the radiometer still worked. Undamaged. Must be because, when it flashed white, I turned off the oven in about 1/4 second.
@tenlittleindians3 ай бұрын
@@wbeaty I think the verdict is still out on your microwave test results. I realize there are insulated crucibles for melting metals in microwaves these days but I still don't quite understand how they work. For instance, the entire inside of a microwave oven is metal yet it barely gets warm during use. A microwave cookbook will have you put aluminum foil around a fishes head and tail to prevent those areas from cooking by blocking the radio waves. A metal can over a tube in a tube radio works as a shield against radio waves and doesn't concentrate heat inside the tube to an extreme degree. And why don't high powered vaccuum tubes have their metal components melt from radio waves? The gas glow you mention sounds similar to sticking a floresent bulb near a Tesla coil. I had read the gas concentrations in these toys was very low so glowing bright white seems extreme! I guess it's just a bit more of a mystery now.
@wbeaty3 ай бұрын
@@tenlittleindians Microwave ovens will heat resistors such as carbon or silicon-carbide. Those "microwave kiln" glass-melting kits use a hollow white cylinder of firebrick with gray paste made of SiC coating the inner surface. The paste layer heats red hot. See videos on DIY microwave glass-slumping art, etc. Or, graphite crucibles can heat to glowing temperatures, to melt the lower-temp metals (not melt steel, just Al Cu Ag Au etc.,) but I think need protection so they don't just burn like charcoal. Microwaves heat the graphite, but not the melting metal. The oven walls stay cold, because the steel is a fairly good reflector and shield. It may have many tens of amps, but that's spread out over large area. The metal plate is "shorting out" the radio energy, forming a standing-wave pattern. There's extremely high voltage in the chamber, but the voltage across any metal surface is nearly zero. (The metal is a node in the standing waves, and the first HV antinode is at 1/4 wave of 2.5GHz, or 3cm. Food stays cold unless it's lifted an inch away from the oven bottom. Insects live happily, as long as they're not over 1cm tall (and not sitting on the glass dish!) Transmitting tubes only get hot when running well over 50 watts. Bad SWR in your ham radio transmitter can make the plate-anode glow red. Or, in large audiophile tube-amps, overdriving the final stage will give red glowing plates. That's why we use graphite-anode tubes like CV-11 or 813H, if using vintage glass tubes. They can take the high plate dissipation. Modern tubes have the plate connected to heatsink fins, with a big blower, and no transparent glass parts. Radiometers have about ten millitorr pressure. Compare with neon signs which have more like 1000 mTorr. A small hand-held Tesla coil makes a radiometer glow dim violet, but makes a neon sign light up extremely bright. My 200-watt vacuum tube Tesla coil driver will make a radiometer glow dimly, and the vanes start turning, as if a flashlight was shining on them. In the microwave oven, the radiometer lights up roughly like a thirty-watt light bulb. But a small fluorescent tube in the microwave oven will light up like a kilowatt light bulb. Just nuking an 8in fluorescent tube for two seconds will make it too hot to touch. Do it over thirty seconds, and the glass softens, and blows bubbles (bursting outwards! The plasma is like a blow torch, and makes the pressure rise from near vacuum to well over atmospheric pressure.)
@tenlittleindians3 ай бұрын
@@wbeaty I read that radiometers were developed while trying to figure out why sunshine changed the weight of things being weighed. Since they showed microwaves can excite a radiometer an cause it to spin I guess it disproves sunlight from being the cause of the spinning.
@TheBigFatVladimirАй бұрын
Thermal transpiration is the most accurate theory by far, it follows the physics properly.
@jaydenwilson952213 күн бұрын
I thought it was trying to achieve thermal equilibrium! Thanks for the term "Thermal transpiration" as I was just saying it was creating a spiral from trying to reach thermal equilibrium.
@franzliszt31955 ай бұрын
Indeed, very interesting. Wonder if the movement due to light has anything to do with Nitrogen gas spectral absorption lines?
@TheBigFatVladimirАй бұрын
No, a Crooke's radiometer works with hot water poured over it or cold ice pack draped over it if you wish so it is not dependent on light.
@EL-bw3xe11 күн бұрын
did you miss the electrostatic test?
@TheBigFatVladimir11 күн бұрын
@@EL-bw3xe The test he did was terribly executed which does not excuse it not working, get a Crooke's radiometer and pour hot water over it, it works, that's fact, theory disproven that fast, thermal transpiration is the accepted theory by physicists, nothing more to it, no need for this lazy testing.