CBSE Class 10 Science 2020 · Paper 31/4/1 · Question 22

Light - Reflection and Refraction 3 marks Medium

The refractive index of a medium ‘x’ with respect to a medium ‘y’ is

2/3

and the refractive index of medium ‘y’ with respect to medium ‘z’ is

4/3

. Find the refractive index of medium ‘z’ with respect to medium ‘x’. If the speed of light in medium ‘x’ is

3 \times 1 0^{8} ms^{- 1}

, calculate the speed of light in medium ‘y’.

Answer

$n_{z x} = \frac{9}{8}$ and the speed of light in medium y is $2 \times 1 0^{8} m s^{- 1}$ .

The refractive index of z with respect to x is

n_{z x} = n_{z y} \times n_{y x} = \frac{3}{4} \times \frac{3}{2} = \frac{9}{8}

(that is,

1.125

). The speed of light in medium y is

v_{y} = \frac{v _{x}}{n _{y x}} = \frac{3 \times 1 0 ^{8}}{3/2} = 2 \times 1 0^{8} m s^{- 1}

🔒 Step-by-step solution