Total internal reflection of a ray of light is possible when the ray goes from
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → denser to rarer medium and the angle of incidence is greater than the critical angle
Total internal reflection needs two conditions. The light must travel from an optically denser to a rarer medium, because only then does the refracted ray bend away from the normal and the angle of refraction reach \( 90^\circ \). The angle of incidence must also be greater than the critical angle \( C \), where \( \sin C = n_2/n_1 \); then no refracted ray exists and all the light is reflected.
Option (1) denser to rarer medium and the angle of incidence is greater than the critical angle — Correct. Both conditions are satisfied.
NCERT (2026-27):
Total Internal Reflection – “When light travels from an optically denser medium to a rarer medium at the interface, it is partly reflected back into the same medium and partly refracted to the second medium.”
Total Internal Reflection – “… The angle of incidence corresponding to an angle of refraction 90°, say ∠AO3N, is called the critical angle (ic) for the given pair of media. … For values of i larger than ic, Snell’s law of refraction cannot be satisfied, and hence no refraction is possible.”