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JEE Main 202523 JanuaryEvening Shift
Exam
JEE Main
Year
2025
Date
23 January
Shift
Evening Shift
Subject
Physics
Chapter
Electromagnetic Waves

JEE Main 2025 · 23 January · Evening Shift · Physics · Electromagnetic Waves

A plane electromagnetic wave of frequency 20 MHz travels in free...

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=9.3Vm−1\mathrm{E}_y=9.3 \mathrm{Vm}^{-1}. Then, the magnetic field vector of the wave at that point is

Options

  1. ABz=6.2×10−8 T\mathrm{B}_z=6.2 \times 10^{-8} \mathrm{~T}
  2. BBz=3.1×10−8 T\mathrm{B}_z=3.1 \times 10^{-8} \mathrm{~T}
  3. CBz=1.55×10−8 T\mathrm{B}_z=1.55 \times 10^{-8} \mathrm{~T}
  4. DBz=9.3×10−8 T\mathrm{B}_z=9.3 \times 10^{-8} \mathrm{~T}

Correct answer

B. Bz=3.1×10−8 T\mathrm{B}_z=3.1 \times 10^{-8} \mathrm{~T}

Step-by-step solution

E=BC9.3=B×3×108 B=9.33×108=3.1×10−8 T\begin{aligned} & \mathrm{E}=\mathrm{BC} \\ & 9.3=\mathrm{B} \times 3 \times 10^8 \\ & \mathrm{~B}=\frac{9.3}{3 \times 10^8}=3.1 \times 10^{-8} \mathrm{~T}\end{aligned}
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