# Lorentz model and dielectric

bahaar
Hi
I read in text for calculation dielectric constant in Lorentz model, we only regard electric field that coupled with each oscillator. So the magnetic field of input wave has no effect in calculation of dielectric constant in this model?

That's not the only reason. While B itself may be weak, the change of B with t $\partial B/\partial t=\rot E$ may be comparable to the electric field itself. However in the case of visible optics, the wavelength over which the electric field changes is much larger than the size of atoms or molecules, so that this effect is usually negligible, too. However it explains e.g. phenomena like optical activity.