Dipole Radiation: Practical Considerations

[sliorbra]

Hi,

I an reading an interesting chapter of Feyman where he explains the basis of light-matter interaction with wave theory: http://cua.mit.edu/8.421_S08/Reading/Feyman_refr_index.pdf

I didn't understand there one thing... to explain it he says that all the dipoles on the plate ''feel'' the same electric field with the same phase [page 4, equation 31.10]. to say this the plate has to be very very very thin [something like 0.1 of the wavelength]... how this can be practical??


Lior

 

[jtbell]

On the first page, about halfway down, he writes:

A source which we shall call "the external source is placed a large distance away from a thin plate of transparent material, say glass.

I added the boldface to point out the key word in his assumptions. He's assuming the plate is indeed very very thin, much less than a wavelength. It's not very practical, but one can build a more practical solution from it by integration.