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JEE Main 2025 (23 Jan, Shift 2) · Nature of EM Waves & Wave Equation

Nature of EM Waves & Wave Equation question from JEE Main 2025 (23 Jan, Shift 2)

Q9JEE Main 2025 · 23 JAN · SHIFT 2Medium

Nature of EM Waves & Wave Equation

A plane electromagnetic wave of frequency 20 MHz travels in free space along the +x+x direction. At a particular point in space and time, the electric field vector of the wave is Ey=9.3 V m−1E_y = 9.3\text{ V m}^{-1}. Then, the magnetic field vector of the wave at that point is

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Answer: (c)

  1. B=Ec=9.33×108=3.1×10−8B = \dfrac{E}{c} = \dfrac{9.3}{3\times10^{8}} = 3.1\times10^{-8} T (frequency is not needed).
  2. y^×z^=x^\hat y\times\hat z = \hat x, so B⃗\vec B is along zz.
  3. So the answer is (c) Bz=3.1×10−8B_z = 3.1\times10^{-8} T.
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