Transverse nature of electromagnetic waves are/is evident by:
A. Interference
B. Dispersion
C. Polarisation
D. Diffraction
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → C only
Polarisation means restricting the vibrations of a wave to one direction perpendicular to its motion. Only a transverse wave has vibrations perpendicular to its direction of travel, so only a transverse wave can be polarised.
(A) Interference — Incorrect. Interference is shown by all waves, including longitudinal sound waves, so it does not reveal transverse nature.
(B) Dispersion — Incorrect. Dispersion comes from the dependence of speed on wavelength in a medium; it says nothing about the direction of vibration.
(C) Polarisation — Correct. A longitudinal wave cannot be polarised, so polarisation shows that light is transverse.
(D) Diffraction — Incorrect. Sound waves also diffract, so diffraction is common to transverse and longitudinal waves.
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.”