Question

The Sun delivers an average power of
926 W/m2 to the top of the Earth’s atmosphere.
The permeability of free space is 4p×10-7 T · N/A and the speed oflight is
2.99792 × 108 m/s.
Find the magnitude of Em for the electromagnetic waves at the topof the atmosphere.
Answer in units of N/C.

I understand that you have to use:

S=e.cE^2

c-2.99792e8

e.- 8.85e-12

S- gives as 926

Could it be that I need to conver S avg to S.(Smax)?