A plane electromagnetic wave having a frequency f = 23.9 GHz propagates along the positive z-direction in free space. The peak value of the Electric Field is 60 V/m. Which among the following is the acceptable magnetic field component in the electromagnetic wave?

$$B_0 = \frac{E_0}{c} = \frac{60}{3 \times 10^8} = 2 \times 10^{-7}\ \text{T}$$

$$\omega = 2\pi f = 2 \times 3.1416 \times 23.9 \times 10^9 \approx 1.5 \times 10^{11}\ \text{rad/s}$$

The wave number, $$k = \frac{\omega}{c}$$:  $$k = \frac{1.5 \times 10^{11}}{3 \times 10^8} = 0.5 \times 10^3\ \text{m}^{-1}$$

Since the wave propagates along the positive z-direction, the argument of the sinusoidal function must be in the form $$(kz - \omega t)$$.