Question

The speed of light in diamond is $125,000$ $km{s}^{-1}$. What is its refractive index ? (Speed of light in air = $3\times {10}^{8}m{s}^{-1}$).

• A. $1/2.4$
• B. $2.4$
• C. $1.2$
• D. $1/1.2$

Answer 1

The correct option is B $2.4$

According to Snell's Law: $\frac{n_2}{n_1}=\frac{v_1}{v_2}$ and R.I for air is $1$
Substituting, $\frac{n_2}{1}=\frac{3\times {10}^8}{1.25\times {10}^8}$
Therefore, $n_2=2.4$