Question

The refractive index of glass is 1.5 and that of water is 1.3, the speed of light in water is 2.25 × 10^8 m/s. What is the speed of light in glass?

(a) 7.95 × 10^8 m/s

(b) 9.95 × 10^8 m/s

(c) 1.95 × 10^8 m/s

(d) 3.95 × 10^8 m/s

I got this question in an interview for job.

My question is from Wave Optics topic in division Wave Optics of Physics – Class 12

Answer 1

Correct option is (c) 1.95 × 10^8 m/s

Easiest explanation: \( \frac {v_g}{v_w} = \frac {\mu_w}{\mu_g}\)

Vg = \((\frac {\mu_w}{\mu_g})\) × vw

\(\frac {v_g}{v_w} = ( \frac {1.3}{1.5} ) \) × 2.25 × 10^8

\(\frac {v_g}{v_w}\) = 1.95 × 10^8 m/s.