Question

3. The refractive indices of glass and water with respect to air are
3 4
and respectively. If speed of
2 3
light in glass is 2 x 100000000 m/s, find the speed of light in water.
​

Answer 1

Answer:

3. The refractive indices of glass and water with respect to air are

3 4

and respectively. If speed of

2 3

light in glass is 2 x 100000000 m/s, find the speed of light in water.

Answer 2

Answer:

Given : n

water

=

3

4

n

glass

=

2

3

v

glass

=2×10

8

m/s n

air

=1

Speed of light in a medium v

medium

=

n

c

where c and n are the speed of light in vacuum and refractive index of medium respectively.

(a) : v

glass

=

n

glass

c

∴ 2×10

8

=

(3/2)

c

⟹c=3×10

8

m/s

(b) : v

water

=

n

water

c

∴ v

water

=

(4/3)

3×10

8

=2.26×10

8

m/s