Consider the following instantaneous representation of a standing wave: ex = v3e, sin(bz) cos(wt), hy = -v3 cos(bz) sin(wt). as a function of z: a) calculate the instantaneous electric field energy density. [2 points] b) calculate the instantaneous magnetic field energy density. [2 points] c) what is the relationship between the instantaneous electric field energy density and the instantaneous magnetic field energy density? explain your answer. [2 points) d) calculate the instantaneous poynting vector. [2 points] e) calculate the instantaneous energy velocity. (use dimensional analysis to assist you in obtaining this expression if you do not remember it.)