Transverse wave nature of light is shown by which phenomenon?

The correct answer is Option (2) → Polarization

In a transverse wave the vibrations are perpendicular to the direction of travel, so they can be confined to one plane. Polarisation is the restriction of the vibrations to a single direction, and it is possible only for transverse waves; a longitudinal wave such as sound, vibrating along its direction of travel, cannot be polarised.

Option (1) Reflection — Incorrect. Reflection happens for all waves, transverse or longitudinal (an echo is reflected sound).

Option (2) Polarization — Correct. Only transverse waves can be polarised, so polarisation proves that light is transverse.

Option (3) Interference — Incorrect. Interference shows the wave nature of light, but sound waves interfere too, so it cannot tell transverse from longitudinal.

Option (4) Diffraction — Incorrect. Diffraction also occurs for longitudinal waves (sound bends round corners), so it shows only the wave nature.

Note: A similar question was also asked in CUET (UG) 2025 on 21-05-2025 (Slot 1).

NCERT (2026-27):
Polarisation – “… Light waves are transverse in nature; i.e., the electric field associated with a propagating light wave is always at right angles to the direction of propagation of the wave. This can be easily demonstrated using a simple polaroid.”