Q84 / 90 · JEE Main 2021 (27 Aug Shift 2) · Physics

A plane electromagnetic wave with a frequency of $30 MHz$ travels in free space. At a particular point in space and time, the electric field is $6 V m^{- 1}$ . The magnetic field at this point will be $x \times 10^{- 8} T$ . The value of $x$ is,

Correct answer: 2

Solution

Recall the formula of the magnitude of the magnetic field in terms of the magnitude of the electric field,

B = \frac{E}{c} = \frac{6}{3 \times 10^{8}} = 2 \times 10^{- 8} T

, here

c

is the speed of light in a vacuum.

Hence, the correct answer is 2.