Question

The difference of speed of light in the two media A and B(υA – υB) is 2.6 × 107 m/s. If the refractive index of medium B is 1.47, then the ratio of refractive index of medium B to medium A is: (Given: speed of light in vacuum C = 3 × 108 ms–1)

• A. 1.303
• B. 1.318
• C. 1.13
• D. 0.12

Answer 1

Answer: (C)

1.13

Answer 2

Speed of light in a medium = $\frac cn$
According to the question
$\frac {c}{n_A} - \frac {c}{n_B} = 2.6×10^7$

$⇒ \frac {n_B}{n_A}−1 = \frac {2.6×10^7}{3×10^8}×n_B$

$⇒ \frac {n_B}{n_A} ≃ 1.13$

So, the correct option is (C): $1.13$