Question

Light propagates $2 \, cm$ distance in a glass of refractive index $1.5$ in time $t_{0}$ . In the same time $t_{0}$ , light propagates a distance of $2.25 \, cm$ in a medium. The refractive index of the medium is

• A. $\frac{4}{3}$
• B. $\frac{3}{2}$
• C. $\frac{8}{3}$
• D. None of these

Answer 1

Answer: (A)

For a given time, optical path remains constant
$\therefore \mu _{1} x_{1} = \mu _{2} x_{2}$
$\text{or} 1 \text{.} 5 \times 2 = \mu _{2} \times 2 \text{.} 2 5$
$\therefore \mu _{2} = \frac{1 \text{.} 5 \times 2}{2 \text{.} 2 5} = \frac{2}{1 \text{.} 5} = \frac{2 0}{1 5} = \frac{4}{3}$