I was wondering about what physically happens when light is transmitted through a non-magnetic medium. Specifically, I’m trying to visualize how materials slow down light as the electromagnetic wave is passing through, and how permittivity affects this. I know that the index of refraction is directly related to relative permittivity, but I’m unclear as to how this parameter affects the speed of propagation.
My understanding of permittivity is that it measures how easily the molecules of the medium can polarize due to the electric field component of light, with larger permittivity meaning easier polarization of the dipole moments. These polarized molecules in turn have a growing/shrinking electric field between the poles that eventually counteracts the initial field that polarized them.
I’m thinking that this time-varying electric field creates a magnetic field, which then creates an electric field, which then creates a magnetic field and so on, and the speed of the light traveling through the medium is dependent on how quickly these fields rise and collapse. This would suggest that my interpretation of a larger permittivity would cause faster propagation, but I know from the equation that a larger permittivity means a larger index of refraction and a slower propagation of light.
My reasoning is flawed, but I’m not sure where I went wrong. I'm thinking that my understanding of permittivity is incorrect. I was hoping someone could shed some light on what physically happens as the waves propagate through a medium, and how this relates to permittivity. If you have any suggestions on websites or links I should look at it would also be greatly appreciated.