If the absolute refractive indices of glass and water are 3/2 and 4/3 respectively, what will be the ratio of velocity of light in glass and water ?
3 : 4
4 : 3
8 : 7
8 : 9
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC NDA-1 – 2017
Given the absolute refractive index of glass, n_g = 3/2.
The speed of light in glass, v_g = c / n_g = c / (3/2) = 2c/3.
Given the absolute refractive index of water, n_w = 4/3.
The speed of light in water, v_w = c / n_w = c / (4/3) = 3c/4.
The ratio of the velocity of light in glass and water is v_g / v_w.
v_g / v_w = (2c/3) / (3c/4) = (2c/3) * (4/3c) = (2/3) * (4/3) = 8/9.
The ratio is 8 : 9.