Question

The speed of light in water and glass is 2.2×10⁸ m/s and 2×10^⁸ m/s, respectively. What is the refractive index of glass with respect to water?

• A. 1
• B. 1.1
• C. 0.909
• D. 0.8

Answer 1

The correct option is B

1.1

Step 1: Given

Speed of light in water $\left(v_1\right)=2.2\times {10}^{8}m/s$

Speed of light in the glass $\left(v_2\right)=2\times {10}^{8}m/s$

Step 2: Formula used

Refractive index is the ratio of the velocity of light in vacuum (c) to the velocity in a specific medium (v).

$n=\frac{c}{v}$…………(1)

Step 3: Finding refractive index of glass with respect to water

Using equation (1)

$n=\frac{v_1}{v_2}$

$$\begin{gathered} n=\frac{2.2\times {10}^8}{2\times {10}^8} \\ n=1.1 \end{gathered}$$

Hence, option (B) n = 1.1 is correct.