Chapter 32.4, Problem 32.4TYU

Figure 32.13 shows one wavelength of a sinusoidal electromagnetic wave at time t = 0. For which of the following four values of x is (a) the energy density a maximum; (b) the energy density a minimum; (c) the magnitude of the instantaneous (not average) Poynting vector a maximum; (d) the magnitude of the instantaneous (not average) Poynting vector a minimum? (i) x = 0; (ii) x = λ/4; (iii) x = λ/2; (iv) x = 3λ/4.