Today in lecture I learned that when light is polarized up and down (perpendicular to the plane of the incident beam) it is always reflected by some amount upon changing its medium of propagation, but when it is polarized side to side (parallel to the plane of the incident beam), there is an angle at which it can be transmitted 100% (Brewster's angle). I understand this in terms of the mathematical derivation, each step is understood and you can finally come up with a relation between the reflection coefficient and the incidence angle, and will see that for the perpendicular polarization case the coefficient is never zero, but for the parallel case the graph passes 0% reflection at a certain angle dependent on the indices of refraction. I am having trouble understanding it conceptually, however, and I feel that I should. My professor said that when you imagine the forced oscillation of the electrons caused by the incident electric field, and then their resulting electric field, you will see by the polarization that the opposing forced electric field can become 0, I assume not its magnitude but it can become perpendicular to the incident electric field. Can anyone help me understand this with an explanation, or a link, or a picture? I'm having trouble understanding why the phase of the reflected light also switches between parallel and perpendicular polarization.