# Calculating the Bohr radius or velocity of an excitons

1. Jan 7, 2010

### supercali

while doing some calculations such as calculating the Bohr radius or velocity of an excitons in semiconductors such as GaAs I didnt understand why is it allowed to use the static permittivity even though the electron and hole aren't as heavy and the spectra is measured at high frequencies such as $$\omega=10^{15}Hz$$?

2. Jan 8, 2010

Re: Excitons

anyone ???