Refractive index of water with respect to air is 4/3 and glass is 3/2

Question

(i) Refractive index of water with respect to air is 4/3 and glass is 3/2. What is the refractive index of glass with respect to water?
(ii) A concave mirror of focal length 10 cm is placed at a distance of 35 cm from a wall. How far from the wall an object be placed so that its image formed by the mirror falls on the wall?

Answer 1

(i) When there are three medias air, water and glass, We have,

∴ Refractive index of glass with respect to water is 9/8.

(ii) Here, f = – 10 cm; v = – 35 cm (since the image is formed on the wall and distance between the wall and mirror is 35 cm). Image is beyond 2f so object has to be in between F and C. Let the distance of the object from the wall be x.