Question

The optical path of a monochromatic light is the same when it goes through $2.00\text{cm}$ of glass or $2.25\text{cm}$ of water. If the refractive index of water is $1.33$. What is the refractive index of glass?

• A. $1.67$
• B. $1.5$
• C. $1.8$
• D. $1.9$

Answer 1

The correct option is B $1.5$

Given :-
${\mu }_w=1.33x_w=2.25\text{cm}{x}_g=2.00\text{cm}$

For same optical path :
${\mu }_g{x}_g={\mu }_w{x}_w$
${\mu }_g=\frac{1.33\times 2.25}{2.00}$
${\mu }_g=1.5$
$\begin{array}{c}\text{Why this question?}\\ \text{Note:- When light travels through a distance x in a medium of refractive index}\mu ,\text{its optical path is}\mu x.\end{array}$