Question

The speed of light in air is 3×10^8ms^-1 and in glass is 2×10^8ms^-1. What is the refractive index of the glass?​

Answer 1

According to Snell's Law:
sin r
sin i
​
=
n
1
​

n
2
​

​
=
v
2
​

v
1
​

​
and Refractive Index for air is ≈1

Substituting,
1
1.5
​
=
v
2
​

3×10
8

​


Therefore, v
2
​
=
1.5
3×10
8

​
=2×10
8
m/s

Answer 2

Given :-

• The speed of light in air is 3×10^8ms^-1 and in glass is 2×10^8ms^-1.

To Find :-

• What is the refractive index of the glass.

Solution :-

Ratio of the speed of light in vacuum to the speed of light in glass.

Refractive index of glass, aμg = velocity of light in air / velocity of light in glass

aμg = 3 × 10⁸ / 2 × 10⁸ = 3/2 = 1.5

Note :-

Friend memories the formula.

Formula :- aμg = speed of light in vacuum or air (c) / speed of light in the median.

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