In Snell's law of refraction, the refractive index of the second medium with respect to the first medium ($n_{21}$) is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → independent of the angle of incidence.
According to Snell’s law,
$n_{21} = \frac{\sin i}{\sin r}$
The refractive index $n_{21}$ depends on the optical properties of both media and is independent of the angle of incidence for a given wavelength of light.
Correct option: Independent of the angle of incidence.