I am puzzled by the fact that the the index of refraction
calculated as the sqr(dielectric_constant) is always
larger, typically by a factor of 2 or 3, than what is
measured in optics. To remove the inconsistency I
would have to assume that the index of refraction
at optical frequencies is much lower than what it is
in electrostatics. Why is it so?
Ludwik Kowalski