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If you buy 2 or more (up to 50), the price will be $17.95 each.
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The Radiometer provides an introduction to the study of thermodynamics that sits on your desk or tabletop. Set it in sunlight or incandescent light and watch the mill inside spin!
The radiometer consists of four vanes, each has one blackened side and one silvered side. It is encased in a clear glass bulb that has a near perfect vacuum. So what happens to make the radiometer "work"?
William Crookes originally believed that sunlight falling on the light-mill turned the vanes so that the black surfaces were being pushed away by the light. He thought that this demonstrated that light radiation pressure on the black vanes was turning it around just like water in a water mill.
The problem with Crookes' explanation is that light falling on the black side should be absorbed, while light falling on the silver side of the vanes should be reflected. This means that there would be twice as much radiation pressure on the metal side as on the black and the mill would actually turn in the opposite way.
What really happens is that the faster molecules from the warmer side of each vane strike the edges obliquely and impart a higher force than the colder molecules. The movement of the vane as a result of tangential forces around the edges is away from the warmer gas and towards the cooler gas with the gas passing around the edge in the opposite direction. Therefore, the movement is actually due to what happens near the edges of the vanes rather than at the faces.
Try it out yourself and watch thermodynamics in action! The radiometer's four vane rotor spins continuously up to 3,000 RPM. It is 6" high and 3" in diameter.
Ikiwa ununue picha mbili au zaidi (hadi 50), bei itakuwa $ 17.95 kila moja. Inapatikana kwa ajili ya ufungaji wa zawadi! Radiometer ni kifaa cha kuanzisha masomo ya thermodynamics ambayo iko kwenye dawati lako au meza. Weka kwenye nuru ya jua au taa ya incandescent na uangalie kinu kilicho ndani kikizunguka! Radiometer ina paneli nne, kila moja ikiwa na upande mmoja ulio nyeusi na upande mmoja ulio na fedha. Imefunikwa katika balbu ya kioo iliyo wazi ambayo ina utupu karibu kamilifu. Kwa hiyo ni nini hutokea ili kufanya kipima-mionzi "ichukue hatua"? Mwanzoni, William Crookes aliamini kwamba mwangaza wa jua uliokuwa ukiangukia kwenye kinu hicho cha taa uligeuza magurudumu hayo ili nyuso nyeusi zikatoke. Alidhani kwamba hii ilionyesha kwamba shinikizo la mnururisho wa mwanga kwenye vipepeo vya nyeusi lilikuwa likizunguka kama maji katika kinu cha maji. Tatizo la ufafanuzi wa Crookes ni kwamba nuru inayopanda upande mweusi inapaswa kunyonya, huku nuru inayopanda upande wa fedha ya paneli inapaswa kuonyeshwa. Hii inamaanisha kuwa kuna shinikizo la mionzi mara mbili zaidi upande wa chuma kuliko upande mweusi na kinu kitazunguka kwa njia tofauti. Kwa kweli, molekuli zenye mwendo wa kasi kutoka upande wenye joto zaidi hupiga kingo kwa njia ya mviringo na kutoa nguvu kubwa kuliko molekuli zenye baridi zaidi. Mzunguko wa fan kama matokeo ya nguvu tangential kuzunguka kingo ni mbali na gesi ya joto na kuelekea gesi baridi na gesi kupita kuzunguka kingo katika mwelekeo kinyume. Kwa hiyo, mwendo ni kweli kutokana na nini hutokea karibu kingo ya panels badala ya katika nyuso. Jaribu mwenyewe na uangalie thermodynamics ikitenda! Radiometer ina rotor nne za kugeuka kwa kasi hadi RPM 3000. Ina urefu wa inchi 6 na kipenyo cha inchi 3.