Re: [amsat-bb] Mystery effect

["Tony Langdon, VK3JED" <vk3jed@xxxxxxxxxxxxxxxx>]

At 07:00 AM 21/12/2001 -0500, you wrote:

>The common radiometers with black and white vanes are not enclosed in a 
>vacuum.  There is a low pressure atmosphere in the glass dome.  The vanes 
>actually rotate the reverse direction to what photon recoil would 
>predict.  The vanes are driven by the gas atoms recoiling from the 
>different temperature vane surface.

I remember studying this phenomenon in high school physics when learning 
the proof that light can act as a stream of particles, and going through 
the different experiments that were used to test the theory.  I found the 
radiometer fascinating, because of the "reverse effect", due to the 
pressure of heated air molecules on the dark side of the vanes.

73 de Tony, VK3JED
http://www.qsl.net/vk3jed

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