PYQ NEET- Electromagnetic Waves L-5

Question: For a plane electromagnetic wave propagating in $\mathrm{x}$-direction, which one of the following combination gives the correct possible directions for electric field $(E)$ and magnetic field $(\mathrm{B})$ respectively? (NEET-2021)#

A) $-\hat{j}+\widehat{k},-\hat{j}+\widehat{k}$

B) $\hat{j}+\widehat{k}, \hat{j}+\widehat{k}$

C) $-\hat{j}+\widehat{k},-\hat{j}-\widehat{k}$

D) $\hat{j}+\widehat{k},-\hat{j}-\widehat{k}$

Answer: $-\hat{j}+\widehat{k},-\hat{j}-\widehat{k}$#

Explanation#

Wave in $\mathrm{x}$ direction

$C=\vec{E} \times \vec{B}$

$(-\hat{j}+\widehat{k}) \times(-\hat{j}-\widehat{k})$

$=\hat{i}+\hat{i}$

$=2 \hat{i}$