CUET · PHYSICS · PYQ PAPER 2023

In an electromagnetic wave, if \(\vec{B}\) and \(\vec{E}\) represent the magnetic field and electric field respectively, then the direction of propagation of the electromagnetic wave is along the direction of:

A \(\vec{B}\)
B \(\vec{E}\)
C \(\vec{E} \times \vec{B}\)
D \(\vec{B} \times \vec{E}\)

Verified Solution

Answer & Solution

Correct Answer

(C) \(\vec{E} \times \vec{B}\)

Step-by-step Solution

Detailed explanation

The direction of propagation of an electromagnetic wave is given by the Poynting vector ( \(\vec{S}\) ), which is defined as \(\vec{E} \times \vec{B}\). This cross product ensures that the wave travels in a direction perpendicular to both the oscillating electric and magnetic…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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