Q: The optical path of a monochromatic light is the same if it goes through 4.00 m of glass are 4.50 m of a liquid. If the refractive index of glass is 1.5, what is the refractive index of the liquid ?
Sol: When light travels a distance ‘x’ in a medium of refractive index μ , the optical path is μ x
Given μ1 x1 = μ2 x2
⇒ 1.5 × 4.00 = μ2 × 4.50
μ2 = (1.5 × 4.00)/4.50 = 1.333