Question

When light travels in a transparent medium, the speed of light decreases by a factor of $1.5$ as compared to the speed in vacuum. The refractive index of the material is-

• A. $1.67$
• B. $1.5$
• C. $1.8$
• D. $1.4$

Answer 1

The correct option is B $1.5$

Refractive index is defined as,

$\mu =\frac{\text{Speed of light in vacuum}\left(c\right)}{\text{Speed of light in the medium}\left(v\right)}$

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

Here given, $v=\frac{c}{1.5}$

$\therefore \mu =\frac{c}{c/1.5}=1.5$

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, $\left(\text{B}\right)$ is the correct answer.