Re: Has anyone ever built a Radiometer large enough to generate electricity

Hi Robert

The mechanical radiometer was originally invented to answere the question 
as to whether or not light exerted a force.  It was thought that since 
light reflected from shiny surfaces, if one side of a set of vanes were 
polished and the other side painted black, the reflection of light from 
the polished surface would generate a force that would turn the vanes.  
What was surprising was that device opereated in reverse.  Additional 
study determined that the blacek surface was heated as light fell on it 
and that molecular repulsion was greated from the heated black surface.  
This is the force that drives the radiometer.  The level of vacuum inside 
the the container holding the radiometer is also important.  Too little 
vacuum and aerodynamic drag counteracts the molecular repulsion forces; 
too much vacuum and there are too few molecules to drive the machine.  
Due to the weak driving force building a very large radiometer would not 
be practical due to frictional losses.

I hope this answers your question.
Greg