An electromagnetic wave travels in free space along the $x$-direction. At a particular point in space and time, $\overrightarrow{\mathrm{B}}=2 \times 10^{-7} \hat{\mathrm{j}} \mathrm{T}$ is associated with this wave. The value of corresponding electric field $\overrightarrow{\mathrm{E}}$ at this point is $\_\_\_\_$ $\mathrm{V} / \mathrm{m}$.

JEE Main · 2026 · 02 Apr 2026 · Shift 2 · EM Waves

An electromagnetic wave travels in free space along the

x

-direction. At a particular point in space and time,

B = 2 \times 1 0^{- 7} \hat{j} T

is associated with this wave. The value of corresponding electric field

E

at this point is

____

V / m

(A)60 k
(B) $- 60 \hat{k}$ ✓ Correct
(C)30 k
(D) $- 600 \hat{k}$

Answer: (B)

Solution

For a plane electromagnetic wave the fields satisfy

E = B \times c

, where

c

points along the direction of propagation. With propagation along

+ x

c = 3 \times 1 0^{8} \hat{i} m/s

, so

E = (2 \times 1 0^{- 7} \hat{j}) \times (3 \times 1 0^{8} \hat{i}) = 60 (\hat{j} \times \hat{i}) = - 60 \hat{k}

. The electric field at that point is

- 60 \hat{k} V/m

JEE Main · 2026 · 02 Apr 2026 · Shift 2 · Single correct option

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