Arrange the following media in the decreasing order of their respecti…

The correct answer is Option (1) → A, C, D, B

Light passing from a medium of refractive index n into air has a critical angle given by

    \( \displaystyle \sin C = \frac{1}{n} \)

So the larger the refractive index, the smaller the critical angle. Using the usual values:

    \( \text{Water: } n = 1.33,\; C \approx 48.8^\circ \)
    \( \text{Crown glass: } n = 1.52,\; C \approx 41.1^\circ \)
    \( \text{Dense flint glass: } n = 1.65,\; C \approx 37.3^\circ \)
    \( \text{Diamond: } n = 2.42,\; C \approx 24.4^\circ \)

The decreasing order of critical angle is A, C, D, B.

Note: A similar question was also asked in CUET (UG) 2026 on 21-05-2026 (Slot 2).

NCERT (2026-27):
Total Internal Reflection – “… The refractive index of denser medium 1 with respect to rarer medium 2 will be \( n_{12} = 1/\sin i_c \). Some typical critical angles are listed in Table 9.1.”