Problem 11.2: Forbidden electromagnetic transitions, part 1. (30 points) In class, we explored atomic transitions provoked by an electromagnetic wave. For simplicity, we studied only the leading order effects the so-called electric dipole transitions hy ignoring B and setting k- 7 0 in E. Here we consider the higher-order effects, which mediate so-called \"forbidden\" transitions, which are not truly forbidden, but only forbidden to the eleetric dipole, and hence in general weaker and slower. a) When we considered only the electric field and dropped the magnetic field, it was con- venient to choose a gauge with i only. Now that we want both E and B, we must include A, Onee we have A, it's actually simpler to consider a gauge where = 0, where the electromagnetic wave can be written: A= %s'e"\"'""\"\