Chapter 7.11, Problem 4P

When a current $I$ flows through a resistance $R$, the heat energy dissipated per second is the average value of $R{I}^2$.

Let a periodic (not sinusoidal) current $I(t)$ be expanded in a Fourier series $I(t)={\displaystyle \underset{-\infty }{\overset{\infty }{\sum }}{c}_n}{e}^{120in\pi t}.$ Give a physical meaning to Parseval’s theorem for this problem.