A plane electromagnetic wave of frequency 100 MHz is travelling in vacuum along the x-direction. At a particular point in space and time, B = 2.0× 10⁻⁸k T. (where, k is unit vector along z-direction) What is E at this point? (a) 0.6 j V/m (b) 6.0 k V/m (c) 6.0 j V/m (d) 0.6 k V/m

Answer: (c). Magnitude: E = cB = 3× 10⁸× 2.0× 10⁻⁸ = 6.0 V/m. Direction: E = i needs E = j, since j = i. So the answer is (c) 6.0j V/m.

A plane electromagnetic wave of frequency 100 MHz is travelling in… | JEE Main 2021 (18 Mar, Shift 1)

Q43JEE Main 2021 · 18 MAR · SHIFT 1Easy

Nature of EM Waves & Wave Equation

A plane electromagnetic wave of frequency 100 MHz is travelling in vacuum along the x-direction. At a particular point in space and time, $\vec{B} = 2.0\times 10^{-8}\hat{k}\text{ T}$ . (where, $\hat{k}$ is unit vector along z-direction) What is $\vec{E}$ at this point?

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Answer: (c)

Magnitude: $E = cB = 3\times 10^{8}\times 2.0\times 10^{-8} = 6.0\ \text{V/m}$ .
Direction: $\hat{E}\times\hat{k} = \hat{i}$ needs $\hat{E} = \hat{j}$ , since $\hat{j}\times\hat{k} = \hat{i}$ .
So the answer is (c) $6.0\hat{j}$ V/m.

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Nature of EM Waves & Wave Equation question from JEE Main 2021 (18 Mar, Shift 1)

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