A light ray in passing from water to a medium (a) speeds up (b) slows down. In each case, (i) give one example of the medium, (ii) State whether the refractive index of a medium is equal to, less than or greater than the refractive index of water.

Solution:

(a) When a light ray travels from water to air, it accelerates.

(b) A light ray slows down as it travels from water to a glass medium.

(c) It means that when the speed increases, the medium’s refractive index falls below that of water.

(d) When the speed of the medium is reduced, the refractive index of the medium is greater than that of water.