Question

The refractive index of glass is 1.5. What does it mean?
(Note : $c$ is the velocity of light in vacuum, $v_g$ is the velocity of light in glass.)

• A. $\frac{v_g}{c}=1.5$
• B. $\frac{c}{v_g}=1.5$
• C. $c=1.5$
• D. $v_g=1.5$

Answer 1

The correct option is B $\frac{c}{v_g}=1.5$

Refractive index or absolute refractive index is nothing but the ratio of velocity of light in vacuum to the velocity of light in the given medium.
Therefore, $n=1.5$ means,$\frac{c}{v_g}=1.5$