Question

Light travels at a speed of equation m/s in air. What is the speed of light in glass, which has an index of refraction of 1.5?

Answer 1

Answer:

$2\times 10^{8}\ \text{m/s}$

Explanation:

$n$ = Refractive index of glass = 1.5

$c$ = Speed of light in vacuum = $3\times 10^8\ \text{m/s}$

Refractive index is given by

$n=\dfrac{c}{v}\\\Rightarrow v=\dfrac{c}{n}\\\Rightarrow v=\dfrac{3\times 10^8}{1.5}\\\Rightarrow v=2\times 10^{8}\ \text{m/s}$

The speed of light in the glass is $2\times 10^{8}\ \text{m/s}$.