Question

5. The refractive indices of glass and water with respect to vacuum are 3/2 and
4/3 respectively. If the speed of light in glass is 2x10m/s, find the speed of
light in:
vacuum
water​

Answer 1

Correct Question

The refractive indices of glass and water with respect to vacuum are 3/2 and4/3 respectively. If the speed of light in glass is 2 x 10^8 m/s. Find the speed of light in

a) vacuum b) water.

Solution-

Given that, the refractive index of glass and water with respect to vacuum are 3/2 and 4/3.

Also given that, speed of light in glass is 2 × 10^8 m/s.

Now,

a)

Refractive index = (Speed of light in the air or vacuum)/(Speed of light in medium)

3/2 = (Speed of light in vacuum)/(2 × 10^8)

Speed of light in vacuum = 3/2 × 2 × 10^8

Speed of light in vacuum = 3 × 10^8 m/s.

b)

Refractive index = (Speed of light in the vacuum)/(Speed of light in water)

4/3 = (3 × 10^8)/(Speed of light in water)

Speed of light in water = (3 × 10^8)/(4/3)

Speed of light in water = (9 × 10^8)/4

Speed of light in water = 2.25 × 10^8 m/s

Answer 2

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QuEsTiOn -

The refractive indices of glass and water with respect to vacuum are 3/2 and 4/3 respectively.

If the speed of light in glass is 2x10m/s, find the speed of light in -

1. vacuum

2. water

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SoLuTiOn -

We know that :

• Refractive index of glass = ( 3 / 2 ) .

• Refractive index of water is ( 4 / 3 )

So, Refractive index of glass wrt vacuum :

=>C_{ vacuum ) / 2 × 10 ^ 8 = ( 3 / 2 )

=> C _ { vacuum } = 3 × 10 ^ 8 m / s.

Refractive index of water wrt vacuum :

3 × 10 ^ 8 / C_{ water } = { 4 / 3 }

=> C_{ water } = 2.25 × 10 ^ 8 m / s.

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AnSwEr -

• The speed of light in vacuum is 3 × { 10 } ^ 8 m / s.

• The speed of light in water is 2.25 × { 10 } ^ 8 m / s .

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