Choose the correct statements :(A) The angle of incidence correspondi…

The correct answer is Option (2) → (A), (B), (C) and (E) only

When light goes from a denser to a rarer medium, it bends away from the normal. Snell's law for this case (denser medium of refractive index \( \mu \), rarer medium air) is

    \( \displaystyle \mu \sin i = \sin r \)

(A) The angle of incidence corresponding to an angle of refraction 90° is called critical angle (i_c). — Correct. This is the definition of the critical angle: the refracted ray just grazes the surface.

(B) Refractive index of denser medium \( \mu = \frac{1}{\sin i_c} \) — Correct. Putting \( i = i_c \) and \( r = 90^\circ \) in Snell's law gives \( \mu \sin i_c = 1 \), the refractive index of the denser medium with respect to the rarer one.

(C) For i > i_c, Snell's law of refraction cannot be satisfied. — Correct. For \( i \gt i_c \), \( \mu \sin i \gt 1 \), so there is no angle \( r \) with \( \sin r = \mu \sin i \). No refraction is possible and all the light is reflected.

(D) The refractive index of air increases with decrease in density. — Incorrect. The refractive index of air decreases as its density decreases; hot, less dense air near a road bends light less, which produces a mirage.

(E) Rainbow is the combined effect of dispersion, refraction and reflection of sunlight by droplets — Correct. Sunlight is refracted and dispersed on entering a raindrop, reflected at its back surface and refracted again on leaving.

Note: Statements (A), (B) and (C) of this question are from the latest textbook (2026-27). Statement (E), that a rainbow is the combined effect of dispersion, refraction and reflection of sunlight by droplets, is printed only in the pre-rationalised textbook (2022-23). It was removed from the latest book, and it also appears to be out of the CUET 2026 syllabus.

NCERT (2026-27):
Total Internal Reflection – “… The angle of incidence corresponding to an angle of refraction 90°, say ∠AO₃N, is called the critical angle (i_c) for the given pair of media. … For values of i larger than i_c, Snell’s law of refraction cannot be satisfied, and hence no refraction is possible. The refractive index of denser medium 1 with respect to rarer medium 2 will be n₁₂ = 1/sin i_c.”

NCERT (Pre-rationalised edition, 2022-23):
The Rainbow – “The rainbow is an example of the dispersion of sunlight by the water drops in the atmosphere. This is a phenomenon due to combined effect of dispersion, refraction and reflection of sunlight by spherical water droplets of rain.”