Question

The optical path of a monochromatic light is the same, when it goes either 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 $1.5$

For same optical path,

${\mu }_g{x}_g={\mu }_w{x}_w$

$1.33\times 2.25={\mu }_g\times 2$

$\therefore {\mu }_g=\frac{1.33\times 2.25}{2.00}=1.5$

Hence, $\left(B\right)$ is the correct answer.

$\begin{array}{c}\text{Why this question?}\\ \text{Note:- When light travels through a distance}x\text{in a medium of refractive index}\mu ,\text{its optical path is}\mu x.\end{array}$