Question 48 of 165

A plane electromagnetic wave of frequency $20MHz$ propagates in free space along $x$-direction. At a particular space and time $\vec{E}=6.6\hat{j}V{m}^{-1}$. What is $\vec{B}$ at this point?

A$2.2\times {10}^{-8}\hat{k}T$B$-2.2\times {10}^{-8}\hat{i}T$C$-2.2\times {10}^{-8}\hat{k}T$D$2.2\times {10}^{-8}\hat{i}T$

Show answer and solution▾

Answer: (A) $2.2\times {10}^{-8}\hat{k}T$

It is given that
$\vec{E}=6.6\hat{j}(V{m}^{-1})$.
The relation between the electric, magnetic field and speed of light is $\vec{E}\times \vec{B}=\vec{c}$.

Clearly, $\vec{B}={B}_{0}(\hat{k})$
Using the relation,
$c{B}_{0}=E$
$\Rightarrow {B}_{0}=\left(\dfrac{E}{c}\right)=\dfrac{6.6}{3\times {10}^{8}}=2.2\times {10}^{-8}T$

JEE Main Physics practice question on Electromagnetic Waves (Electromagnetic Waves and Maxwell's equations), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.