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Name: Bruce H.
Status: educator
Age: 50s
Location: N/A
Country: N/A
Date: 9/19/2004

Refraction of light is mainly due to difference in permittivity. Classical theory of dielectrics attributes this to polarisation in which the charge distribution of the atoms is affected by the electric field.

I do not understand how changes in charge distribution can take place within an atom at the rates corresponding to the frequency of light.

Perhaps it will help to consider that molecular vibrations produce infrared radiation (frequencies in to 200 THz range and even higher). This is related to the vibration (movement) of nuclei. Electrons are several orders of magnitude less massive than nuclei.

Greg Bradburn

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