An electromagnetic wave propagating in vacuum is described by \( E = E_{0}\sin(kx-\omega t) \); \( B = B_{0}\sin(kx-\omega t) \). Which one of the following relations is correct?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \( E_{0}\kappa = B_{0}\omega \)
In an electromagnetic wave in vacuum, the ratio of the amplitudes equals the speed of light, and the speed of the wave is \( \omega/k \).
\( \displaystyle \frac{E_{0}}{B_{0}} = c = \frac{\omega}{k} \)
Cross-multiplying:
\( E_{0}k = B_{0}\omega \)
This is Option (2), where \( \kappa \) stands for the wave number \( k \).
Note: It seems that there is a mistake in the original NTA paper, which prints \( \kappa \) in the options when it should read \( k \), the wave number used in the question. The meaning is clear, so the question can still be solved.
Note: A similar question was also asked in CUET (UG) 2026 on 07-06-2026 (Slot 2) and on 25-05-2026 (Slot 1), and in CUET (UG) 2023 on 02-07-2023 (Slot 3) and on 14-06-2023 (Slot 1).