Question

The optical path of a monochromatic light is same if it goes through $4.0cm$ of glass of $4.5cm$ of water. If the refractive index of glass is $1.53$, the refractive index of the water is

• A. $1.30$
• B. $1.36$
• C. $1.42$
• D. $1.46$

Answer 1

The correct option is B $1.36$

Optical path, $\mu x=constant$
i.e., ${\mu }_1{x}_1={\mu }_2{x}_2$
$\Rightarrow 1.53\times 4={\mu }_2\times 4.5$
$\Rightarrow {\mu }_2=\frac{1.53\times 4}{4.5}=1.36$.