Question

Index of refraction is defined as the speed of light in a vacuum divided by the speed of light in the medium. What is the index of refraction for a glass sample? Speed of light in a vacuum c = 3.0 x 108 m/s. Speed of light in the glass = 1.50 x 108 m/s.

Answer 1

Given:

The speed of light in a vacuum is

$c=\text{ 3}\times10^8\text{ m/s}$

The speed of light in glass is

$v=1.5\times10^8\text{ m/s}$

Required: Index of refraction for a glass

Explanation:

The index of refraction is given by the formula

$n=\frac{c}{v}$

On substituting the values, the index of refraction is

$\begin{gathered} n=\frac{3\times10^8\text{ m/s}}{1.5\times10^8\text{ m/s}} \\ =\text{ 2} \end{gathered}$

Final answer: The index of refraction of glass is 2.