Consider a periodic array of slits with a period of A through which light propagates. Let be the angle of incidence. Show that diffraction occurs at angles ' that satisfy the following equation: A sin + A sin 0' = m, m = 1,2,3,... (b) Let z be the direction of periodicity. Show that the equation above can also be written as k-k= m(2/A), m = 1,2,3,...