A plane electromagnetic wave of wavelength λ has an intensity I. It is propagating along the positive Y-direction. The allowed expressions for the…

$$\begin{aligned} & \overrightarrow{\mathrm{E}}=\sqrt{\frac{2 \mathrm{I}}{\epsilon_{\mathrm{o}} \mathrm{c}}} \cos \left[\frac{2 \pi}{\lambda}(y-\mathrm{ct})\right] \hat{k} ; \\ & \overrightarrow{\mathrm{B}}=+\frac{1}{\mathrm{c}} \mathrm{E} \hat{i} \end{aligned} $$

$$\begin{aligned} & \overrightarrow{\mathrm{E}}=\sqrt{\frac{2 \mathrm{I}}{\epsilon_{\mathrm{o}} \mathrm{c}}} \cos \left[\frac{2 \pi}{\lambda}(y+\mathrm{ct})\right] \hat{k} ; \\ & \overrightarrow{\mathrm{B}}=\frac{1}{\mathrm{c}} \mathrm{E} \hat{i} \end{aligned} $$

$$\begin{aligned} & \overrightarrow{\mathrm{E}}=\sqrt{\frac{\mathrm{I}}{\epsilon_{\mathrm{o}} \mathrm{c}}} \cos \left[\frac{2 \pi}{\lambda}(y-\mathrm{ct})\right] \hat{k} ; \\ & \overrightarrow{\mathrm{B}}=\frac{1}{\mathrm{c}} \mathrm{E} \hat{i} \end{aligned} $$

$$\begin{aligned} & \overrightarrow{\mathrm{E}}=\sqrt{\frac{\mathrm{I}}{\epsilon_{\mathrm{o}} \mathrm{c}}} \cos \left[\frac{2 \pi}{\lambda}(y-\mathrm{ct})\right] \hat{i} ; \\ & \overrightarrow{\mathrm{B}}=\frac{1}{\mathrm{c}} \mathrm{E} \hat{k} \end{aligned} $$