Question

In an experiment, a light ray is incident on the air-glass interface as shown in the figure. If the angle of incidence is ${45}^{\circ }$ and angle of refraction is ${30}^{\circ }$, then the speed of light in the glass is -

• A. $1.5\times {10}^8\text{m/s}$
• B. ${10}^8\text{m/s}$
• C. $\sqrt{2}\times {10}^8\text{m/s}$
• D. $\frac{3\times {10}^8}{\sqrt{2}}\text{m/s}$

Answer 1

The correct option is D $\frac{3\times {10}^8}{\sqrt{2}}\text{m/s}$

We know that,

$\frac{\sin i}{\sin r}=\frac{v_1}{v_2}$

$\Rightarrow \frac{\sin {45}^{\circ }}{\sin {30}^{\circ }}=\frac{3\times {10}^8}{v_2}$

$\Rightarrow v_2=\frac{3\times {10}^8}{\sqrt{2}}\text{m/s}$

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