ok, for one of the prioblems I'm given the equations of an electric field:
Ex(z,t) = E0sin(kz-wt)
Ey(z,t) = E0cos(kz-wt)
for a circularly polarized plane wave of light traveling in the z direction.
I have to show the magnetic field, energy density, and Poynting vector for this wave.
the energy density is u = .5 [eE2 + B2/u]
the Poynting vector is S = (E x B)/u
The Attempt at a Solution
I believe I can just plug in the values of E and B directly in the two equations above; however, I am having a tough time finding out what B is. In my textbook it says the general formula is b(z, t) = (k x E)/c, but I don't know how to compute this cross product.