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JEE Main 2023 (24 Jan, Shift 1) · Nature of EM Waves & Wave Equation

Nature of EM Waves & Wave Equation question from JEE Main 2023 (24 Jan, Shift 1)

Q23JEE Main 2023 · 24 JAN · SHIFT 1Easy

Nature of EM Waves & Wave Equation

If E⃗\vec{E}and K⃗\vec{K} represent electric field and propagation vectors of the EM waves in vacuum, then magnetic field vector is given by:

(ω\omega - angular frequency):

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Answer: (a)

  1. For a plane wave ∇×E⃗=−∂B⃗∂t\nabla\times\vec{E} = -\frac{\partial\vec{B}}{\partial t} gives K⃗×E⃗=ωB⃗\vec{K}\times\vec{E} = \omega\vec{B}.
  2. Check magnitude: B=KEω=EcB = \frac{KE}{\omega} = \frac{E}{c}, correct.
  3. B⃗=1ω(K⃗×E⃗)\vec{B} = \frac{1}{\omega}(\vec{K}\times\vec{E}).
  4. So the answer is (a).
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