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CUET · PHYSICS · PYQ PAPER 2023

A plane electromagnetic wave of frequency 50 MHz travels in free space along the z-direction. If at a particular point in space and time, \( \vec{E} = (9.3\hat{j}) \text{ V m}^{-1} \), what is \( \vec{B} \) at this point?

  1. A \( (3.1 \times 10^{-8} \hat{i}) \text{ T} \)
  2. B \( (3.1 \times 10^{-8} \hat{j}) \text{ T} \)
  3. C \( (2.8 \times 10^8 \hat{k}) \text{ T} \)
  4. D \( (3.1 \times 10^{-8} \hat{k}) \text{ T} \)
Verified Solution

Answer & Solution

Correct Answer

(A) \( (3.1 \times 10^{-8} \hat{i}) \text{ T} \)

Step-by-step Solution

Detailed explanation

\( B = E/c \) \( B = 9.3 / (3 \times 10^8) = 3.1 \times 10^{-8} \text{ T} \) \( \hat{E} \times \hat{B} = \hat{k} \Rightarrow \hat{j} \times \hat{B} = \hat{k} \Rightarrow \hat{B} = \hat{i} \) \( \vec{B} = (3.1 \times 10^{-8} \hat{i}) \text{ T} \)