In an electromagnetic wave the electric field vector and magnetic field vector are given as $\vec{E}=E_{0} \hat{i}$ and $\vec{B}=B_{0} \hat{k}$ respectively. The direction of propagation of electromagnetic wave is along.

JEE Main · 2021 · 20 Jul 2021 · Shift 2 · EM Waves

In an electromagnetic wave the electric field vector and magnetic field vector are given as

E = E_{0} \hat{i}

and

B = B_{0} \hat{k}

respectively. The direction of propagation of electromagnetic wave is along.

(A) $(- \hat{k})$
(B) $(\hat{k})$
(C) $(- \hat{j})$ ✓ Correct
(D) $\hat{j}$

Answer: (C)

Solution

The direction of propagation of an electromagnetic wave is given by the Poynting vector

S = \frac{1}{μ _{0}} (E \times B)

. Here,

E = E_{0} \hat{i}

and

B = B_{0} \hat{k}

. Therefore,

E \times B = E_{0} B_{0} (\hat{i} \times \hat{k}) = - E_{0} B_{0} \hat{j}

. The wave propagates along

- \hat{j}

JEE Main · 2021 · 20 Jul 2021 · Shift 2 · Single correct option

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