Question

$A$ plane electromagnetic wave of frequency $500\, MHz$ is travelling in vacuum along y-direction. At a particular point in space and time, $\overrightarrow{ B }=8.0 \times 10^{-8} \hat{ z } T$. The value of electric field at this point is:
(speed of light $=3 \times 10^{8} ms ^{-1}$ )
$\hat{ x }, \hat{ y }, \hat{ z }$ are unit vectors along $x , y$ and direction.

• A. $-24\, \hat{ x }\, V / m$
• B. $2.6\, \hat{ x }\, V / m$
• C. $24\, \hat{ x }\, V / m$
• D. $-2.6\, \hat{ y }\, V / m$

Answer 1

Answer: (A)

$f =5 \times 10^{8} \,HZ$
EM wave is travelling towards $+\hat{j}$
$\overrightarrow{ B }=8.0 \times 10^{-8} \hat{ z }\,T$
$\overrightarrow{ E }=\overrightarrow{ B } \times \overrightarrow{ C }=\left(8 \times 10^{-8} \hat{ z }\right) \times\left(3 \times 10^{8} \hat{ y }\right)$
$=-24\, \hat{ x }\,V/m$