As an electromagnetic wave passes through a small volume, the energy contained within it oscillates with

Step-by-step solution

Let the electric field and magnetic field of the electromagnetic wave be E = E₀ ( t - kx) and B = B₀ ( t - kx) . The energy density of the electromagnetic wave is given by u = 1 2 ₀ E^2 + 1 2 ₀ B^2 . Substituting the expressions for E and B , we get u = 1 2 ₀ E₀^2 ^2( t - kx) + 1 2 ₀ B₀^2 ^2( t - kx) . Using the trigonometric identity ^2 = 1 - (2 ) 2 , the energy density becomes proportional to 1 - (2 t - 2kx) . The time-varying part of the energy density oscillates with an angular frequency of 2 . Since the angula