Question

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

• A. 1.3
• B. 1.36
• C. 1.42
• D. 1.46

Answer 1

Answer: (B)

1.36

Answer 2

As optical paths are equal, hence $n_{g} \cdot x_{g} =n_{w} \cdot x_{w}$ $\Rightarrow n_{w} =n_{g} \cdot \frac{x_{g}}{x_{w}}$ $=1.53 \times \frac{4.0}{4.5}$ $=1.36$