1. The problem statement, all variables and given/known data In the case of total internal reflection, show that the average rate of energy transport across the boundary is zero. 2. Relevant equations None Provided 3. 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.