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

JEE Main · 2021 · 27 Aug 2021 · Shift 2 · EM Waves

A plane electromagnetic wave with frequency of 30 MHz travels in free space. At particular point in space and time, electric field is

6 V / m

. The magnetic field at this point will be

x \times 1 0^{- 8} T

. The value of

x

is ____.

Answer: 2

Solution

For an EM wave in free space, the relationship between electric and magnetic fields is

E = c B

, where

c = 3 \times 1 0^{8}

m/s. Thus

B = \frac{E}{c} = \frac{6}{3 \times 1 0 ^{8}} = 2 \times 1 0^{- 8}

T. Therefore,

x = 2

JEE Main · 2021 · 27 Aug 2021 · Shift 2 · Integer answer

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