Question 143: EM waves

Question

A plane electromagnetic wave of frequency 50 MHz travels in free space along the  positive x-direction. At a particular point in space and time, $$\overrightarrow E  = 6.3\widehat j\,V/m.$$ The corresponding magnetic field $$\overrightarrow {B,} $$ at that point will be :

Accepted Answer

Given, $$\overrightarrow E  = 6.3\widehat j$$
$$ 	herefore $$   $$\left| {\overrightarrow E } ight| = \sqrt {{{\left( {6.3} ight)}^2}}  = 6.3$$
$$ 	herefore $$   $$\left| {\overrightarrow B } ight| = {{\left| {\overrightarrow E } ight|} \over C}$$
$$ = {{6.3} \over {3 	imes {{10}^8}}}$$
$$ = 2.1 	imes {10^{ - 8}}\,$$ T
Now we have to find the direction of $$\overrightarrow B $$.
We know, $$\widehat E 	imes \widehat B = \widehat C$$ and given $$\overrightarrow E $$ is in y-direction and wave moving in positive x-direction.
$$ 	herefore $$   $$\widehat J 	imes \widehat B = \widehat i$$
$$ \Rightarrow $$   $$\widehat B = \widehat K$$
$$ 	herefore $$   $$\overrightarrow B  = \left| {\overrightarrow B } ight|\widehat B$$
$$ = 2.1 	imes {10^{ - 8}}\,\widehat K\,T$$

Answer

18.9 $$ 	imes $$ 10$$-$$8 $$\widehat k$$T

Answer

2.1 $$ 	imes $$ 10$$-$$8 $$\widehat k$$T

Answer

6.3 $$ 	imes $$ 10$$-$$8 $$\widehat k$$T

Answer

18.9 $$ 	imes $$ 108 $$\widehat k$$T

EM waves

A plane electromagnetic wave of frequency 50 MHz travels in free space along the positive x-direction. At a particular point in space and time, $\overrightarrow E = 6.3\widehat j\,V/m. The corresponding magnetic field \overrightarrow {B,} $ at that point will be :

Choose the correct answer: