In the case of total internal reflection, show that the average rate of energy transport across the boundary is zero.
The Attempt at a Solution
All that I have come to is that I should use some form of the following method to find the time average of a product:
<fg> = (1/2)Re<fg*> ....(fg on the RHS can have real and/or imaginary parts)
I am quite lost on this problem and have hit a brick wall for this hw problem. Any help is appreciated, thank you.