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## Homework Statement

ok, for one of the prioblems I'm given the equations of an electric field:

E

_{x}(z,t) = E

_{0}sin(kz-wt)

E

_{y}(z,t) = E

_{0}cos(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.

## Homework Equations

the energy density is u = .5 [eE

^{2}+ B

^{2}/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 dont know how to compute this cross product.

any advice?