In a plane electromagnetic wave, the directions of electric field and magnetic field are represented by $\widehat k$ and $2\widehat i - 2\widehat j$, respectively. What is the unit vector along direction of propagation of the wave?
Solution
$$\overrightarrow E \times \overrightarrow B = \widehat k \times \left( {2\widehat i - 2\widehat j} \right)$$
<br><br>= $2\widehat k \times \widehat i - 2\widehat k \times \widehat j$
<br><br>= $\left( {2\widehat j + 2\widehat i} \right)$
<br><br>Unit vector along $\overrightarrow E \times \overrightarrow B$ = ${{\left( {2\widehat j + 2\widehat i} \right)} \over {2\sqrt 2 }}$
<br><br>= ${1 \over {\sqrt 2 }}\left( {\widehat i + \widehat j} \right)$
About this question
Subject: Physics · Chapter: Electromagnetic Waves · Topic: Properties of EM Waves
This question is part of PrepWiser's free JEE Main question bank. 109 more solved questions on Electromagnetic Waves are available — start with the harder ones if your accuracy is >70%.