This quantity is related to the number of particles times mean polarizability by the Lorentz-Lorenz equation. This quantity can be negative in left-handed metamaterials. (-5[1])This quantity changes linearly in response to an electric field in Pockels effect, and it changes quadratically with the electric field in the Kerr effect. Taking (-5[1])the arctangent (-5[1])of the ratio of two values of this quantity gives Brewster’s angle. The ratio of two values of this quantity equals the (10[2])ratio (10[2])of the sines of two angles in Snell's law. (10[1])For 10 points, dividing the speed of light by the speed of light in (-5[1])a medium gives what quantity that measures how much light bends (10[1])in a medium? (10[1])■END■ (10[2]0[3])