A small coin is resting on the bottom of a beaker filled with liquid. A ray of light from the coin travels upto the surface of the liquid and moves along its surface. How fast is the light travelling in the liquid?

Question

A small coin is resting on the bottom of a beaker filled with liquid. A ray of light from the coin travels upto the surface of the liquid and moves along its surface. How fast is the light travelling in the liquid? (A)  2.4 × 108 m/s (B)  3.0 × 108 m/s (C)  1.2× 108 m/s (D)  1.8 × 108 m/s

Tardigrade Admin · Accepted Answer

<img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/1b6c1708526a80e8a3d9a5cc4bb7ed47-.png" /> (1/μ)= sin θC =(3/5) ⇒ μ=(5/3) ⇒ v =( c /μ) =(3 × 108/5 / 3)=(9/5) × 108 =1.8 × 108 ms -1

Q. A small coin is resting on the bottom of a beaker filled with liquid. A ray of light from the coin travels upto the surface of the liquid and moves along its surface.
How fast is the light travelling in the liquid?

$2.4 \times 10^{8} m / s$

$3.0 \times 10^{8} m / s$

$1.2 \times 10^{8} m / s$

$1.8 \times 10^{8} m / s$

$\frac{1}{μ} = sin θ_{C} = \frac{3}{5}$
$\Rightarrow μ = \frac{5}{3}$
$\Rightarrow v = \frac{c}{μ} = \frac{3 \times 1 0 ^{8}}{5/3} = \frac{9}{5} \times 1 0^{8}$
$= 1.8 \times 1 0^{8} m s^{- 1}$

Q. A small coin is resting on the bottom of a beaker filled with liquid. A ray of light from the coin travels upto the surface of the liquid and moves along its surface. How fast is the light travelling in the liquid?

2.4×108m/s

3.0×108m/s

1.2×108m/s

1.8×108m/s