Question

A light ray enters from medium A to medium B as shown in Figure 10.2. The refractive index of medium B relative to A will be

(a) greater than unity
(b) less than unity
(c) equal to unity
(d) zero

Answer 1

(a) greater than unity

Since light rays in medium B goes towards normal. So it has greater restrictive index and lesser velocity of light with respect to medium A. So refractive index of medium B with respect to medium A is greater than unity.

Comments

it will be option "a"
Refractive index B wrt A =  nBA = V1/V2  = Speed of light in medium A / speed of light in medium B
                                     
Since ray of light bends towards the normal, when it goes from medium A to medium B, therefore, medium A is rarer and medium B is denser, speed in rarer medium (v1) is greater than the speed of light in denser medium (v2) ,so  V1 > V2(improper fraction), hence nBA > 1

n21 greater then 1
i.e V1>V2
then optical density M1 is rarer (A),
M2 is denser.
then bending of ray towards the normal
Conclusion :- Greater the value of RI more is bending towards normal