Question

Speed of light in air is 3 x 10 m/s. Calculate the speed of light in diamond, if the refractive index of diamond is 2.42.​

Answer 1

Given :

Speed of light in air = 3×10⁸ m/s

Refractive index of diamond = 2.42

To Find :

Speed of light in diamond.

Solution :

❖ Refractive index of a medium is defined as the factor by which speed of light reduces as compared to the speed of light in vacuum.

$\dag\:\underline{\boxed{\bf{\purple{\mu=\dfrac{c}{v}=\dfrac{speed\:of\:light\:in\:vacuum}{speed\:of\:light\:in\:medium}}}}}$

More (less) refractive index implies less (more) speed of light in that medium, which therefore is called denser (rarer) medium.

• It is an unitless as well as dimensionless physical quantity.

By substituting the given values;

➙ μ = c / v

➙ 2.42 = (3 × 10⁸) / v

➙ v = (3/2.42) × 10⁸

➙ v = 1.24 × 10⁸ m/s