A plane electromagnetic wave propagating along y-direction can have the following pair of electric field (E) and magnetic field (B) components. (a) Ex, Bz or Ez, Bx (b) Ex, By or Ey, Bx (c) Ey, By or Ez, Bz (d) Ey, Bx or Ex, By

Answer: (a). For propagation along y, E and B must both be perpendicular to y and to each other. So the pair can only be (x, z) or (z, x); any y-component is not allowed. i = -j and k = j, both along the y-axis. So the answer is (a) Ex, Bz or Ez, Bx.

A plane electromagnetic wave propagating along y-direction can have… | JEE Main 2021 (18 Mar, Shift 2)

Q42JEE Main 2021 · 18 MAR · SHIFT 2Easy

Nature of EM Waves & Wave Equation

A plane electromagnetic wave propagating along y-direction can have the following pair of electric field $\left(\vec{E}\right)$ and magnetic field $\left(\vec{B}\right)$ components.

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Answer: (a)

For propagation along y, $\vec{E}$ and $\vec{B}$ must both be perpendicular to y and to each other.
So the pair can only be (x, z) or (z, x); any y-component is not allowed.
$\hat{i}\times\hat{k} = -\hat{j}$ and $\hat{k}\times\hat{i} = \hat{j}$ , both along the y-axis.
So the answer is (a) $E_x, B_z$ or $E_z, B_x$ .

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Nature of EM Waves & Wave Equation question from JEE Main 2021 (18 Mar, Shift 2)

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