Question

What is the relative refractive index of water with respect to glass?

(a) Unity

(b) More than unity

(c) Less than unity

(d) Zero

The question was posed to me in examination.

Enquiry is from Ray Optics topic in section Ray Optics and Optical Instruments of Physics – Class 12

Answer 1

Right option is (c) Less than unity

The explanation: Absolute refractive index = \( \frac {Speed \, of \, light \, in \, vacuum}{Speed \, of \, light \, in \, the \, medium}\). The relative refractive index of water with respect to glass is less than unity.