Question:
A light ray enters from medium A to medium B as shown in figure. The refractive index of medium B relative to medium A will be
(a) greater than unity
(b) less than unity
(c) equal to unity
(d) zero
Solution:
(a).
Explanation:
Explanation : $n_{\mathrm{BA}}=\frac{v_{1}}{v_{2}}$
where v1 = speed of light in medium A
V2 = speed of light in medium B.
Since ray of light bends towards the normal, when it goes from medium A to rrtedium B, therefore, medium A is rarer and medium B is denser
medium. Speed of light in rarer medium (v1) is greater than the speed of light in denser medium (v2). Hence, nBA > 1.