Energy and Momentum in Electromagnetic waves

[desibrij_1785]

Help me...

A sinusoidal electromagnetic wave from a radio station passes perpendicularly through an open window that has area of .5m^2. At the window, the electic field of the wave has rms value of .02 V/m. How much energy does this wave carry through the window during a 30sec commercial?

 

[Doc Al]

Poynting vector describes energy flow

The rate of energy flow per unit area of an electromagnetic wave is given by the Poynting vector:
$$\vec{S} = \frac{1}{\mu_0} \vec{E} \times \vec{B}$$

The magnitude of the Poynting vector can be shown to be:
$$S = \frac{E^2}{c\mu_0}$$

 

[desibrij_1785]

thanks for the reply but i found the answer