Question

Solve:

(1) The speed of light in a transparent medium is 2.4 × 10⁸ m/s. Calculate absolute refractive index of the medium.

(2) The speed of light in water and glass is 2.2 × 10⁸ m/s and 2 × 10⁸ m/s, respectively. What is the refractive index of −

(a) water w.r.t. glass

(b) glass w.r.t. water.

(3) Refractive index of water is 4/3 and speed of light in air is 3×10⁸ m/s. Find speed of light in water.

Answer 1

(1) Given that:

Speed of light in transparent medium, v₂ = 2.4×10⁸ m/s.

Absolute refractive index of the medium, η₂ =?

For absolute refractive index, first medium is vacuum or air,

Speed of light in first medium (vacuum), v₁ = 3×10⁸ m/s.

We have,

Note: Refractive index does not have a unit.

(2) Given that:

Speed of light in water, v₁ = 2.2×10⁸ m/s

Speed of light in glass, v₂ = 2×10⁸ m/s

(a) Refractive index of water w.r.t. glass, ₂η₁ =?

(b) Refractive index of glass w.r.t. water, ₁η₂ =?

(3) Given that:

Refractive index of water, η₂ = 4/3

Speed of light in air, v₁ = 3×10⁸ m/s.

Speed of light in water, v₂ =?