Electromagnetic Waves

JEE Main level, single correct, medium

44 of 165

Question 44 of 165

In an electromagnetic wave, at an instant and at a particular position, the electric field is along the negative z-axis and magnetic field is along the positive x-axis. Then the direction of propagation of electromagnetic wave is:

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Answer: (D) negative y-axis

Direction of propagation of the electromagnetic wave is along E⃗×B⃗\vec{E}\times \vec{B}
Thus,
n⃗=E(−k^)×B(i^)\vec{n}=E\left(-\hat{k}\right)\times B\left(\hat{i}\right)
Therefore,
n^=−k^×i^=−j^\hat{n}=-\hat{k}\times \hat{i}=-\hat{j}

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