Question

20
Refractive index of diamond with respect to vacuum is 2.42
and then the velocity of light in diamond is *
(1 Point
25 x 108m/s
2.5 x 108m/s
1.2 x 108m/s
21 x 108murs​

Answer 1

1.24 × 10⁸ m/s is the required answer.

Option c is right.

GIVEN:

• Refractive index of diamond with respect to vacuum , μ = 2.42

TO FIND:

Velocity of light in diamond, v

FORMULA:

Refractive index, μ = c/v

Where c is the velocity of light in free space or vacuum.

c = 3 × 10⁸ m/s

SOLUTION:

μ = c/v

$2.42 = \dfrac{3 \times {10}^{8} }{v} \\ \\ v = \dfrac{3 \times {10}^{8} }{2.42} \\ \\ v = \dfrac{3}{2.42} \times {10}^{8} \\ \\ v = 1.24 \times {10}^{8} \: \dfrac{m}{s}$

ANSWER:

Velocity of light in diamond is 1.24 × 10⁸ m/s

IMPORTANT POINTS:

• Referactive index is a ratio of two similar quantities. So it has no unit. It is dimensionless.

• Refractive index of a material is inversely proportional to the velocity of light in that medium.

• It means that light travels faster in medium with lower refractive index.

• According to snell's law, refractive index , μ = sin i / sin r