Electromagnetic waves [simple one]

[cupcake]

Homework Statement

Public television station KQED in San Francisco broadcasts a sinusoidal radio signal at a power of 316 kW. Assume that the wave spreads out uniformly into a hemisphere above the ground.


At a home 6.00 km away from the antenna, what is the average density of the energy this wave carries?

For the energy density in part (a), what percentage is due to the electric field?

For the energy density in part (a), what percentage is due to the magnetic field?

Homework Equations

u= P/ (c*a)

u=1/2*epsilon* E^2 + 1/2mu * B^2

The Attempt at a Solution

i managed to do part A, by using equation u=P/(c*a)

i don't know how to get the percentage,, please advise

 

[kuruman]

The equation for the energy density you have quoted is a good starting point. To find the required percentage, you need to have a relation between E and B for plane EM waves. Can you think of one?