Question 121: EM waves

Question

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?

Accepted Answer

$$\overrightarrow E  	imes \overrightarrow B  = \widehat k 	imes \left( {2\widehat i - 2\widehat j} ight)$$
= $$2\widehat k 	imes \widehat i - 2\widehat k 	imes \widehat j$$
= $$\left( {2\widehat j + 2\widehat i} ight)$$
Unit vector along $$\overrightarrow E  	imes \overrightarrow B $$ = $${{\left( {2\widehat j + 2\widehat i} ight)} \over {2\sqrt 2 }}$$
= $${1 \over {\sqrt 2 }}\left( {\widehat i + \widehat j} ight)$$

Answer

$${1 \over {\sqrt 5 }}\left( {\widehat i + 2\widehat j} \right)$$

Answer

$${1 \over {\sqrt 5 }}\left( {2\widehat i + \widehat j} \right)$$

Answer

$${1 \over {\sqrt 2 }}\left( {\widehat i + \widehat j} \right)$$

Answer

$${1 \over {\sqrt 2 }}\left( {\widehat j + \widehat k} \right)$$

EM waves

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?

Choose the correct answer: