In my previous post, I stated that the total energy density of an EM
wave was given by:
U = 1/[2*(permittivity of free space)*E^2] + 
    1/[2*(permeability of free space)*B^2]
This is incorrect. It should actually be:
U = [(permittivity of free space)*(E^2)]/2 + 
    B^2/2*(permeability of free space)
Sorry for any confusion that may have caused.