What is the velocity of light in a diamond if the refractive index of diamond with respect to vacuum is 2.5?

Question

Question

Answer 1

The correct answer is 1.2 × 108 m/s.

Key Points

CONCEPT:

Refractive index (μ): The ratio of the velocity of light in vacuum to the velocity of light in the medium is called refractive index of that medium.

\(\text{The refractive index of a substance/medium}=\frac{\text{Velocity of light in vacuum}}{\text{Velocity of light in the medium}}\)

So μ = c/v

Where c is the speed of light in vacuum and v is the speed of light in the medium.

CALCULATION:

Given that:

Refractive index of the diamond (µ_d)= 2.5

We know

The velocity of light in vacuum (c) = 3 × 10⁸m/s

To find the velocity of light in diamond (v)

Now,

\(μ _d=\frac{c}{v}\\ or, \; 2.5= \frac{3 \times 10^8}{v}\\ or, \; v=\frac{3 \times 10^8}{2.5}=1.2\times 10^8 \; m/s\)

Hence option 1 is correct.

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