Refraction of light at a Plane Interface: Total Internal Reflection: Optical Fibre — Flashcards

Answer

Refraction is the bending of a light ray from its path when it passes from one transparent medium to another at the interface of the two media.

Answer

Refraction occurs because the speed of light changes from one medium to another. Greater the change in speed, greater is the bending of the ray.

Answer

1) The incident ray, refracted ray, and the normal at the point of incidence lie in the same plane. 2) For a given pair of media and a given colour of light, sin i / sin r is constant.

Answer

n1 sin i = n2 sin r, where n1 and n2 are the refractive indices of the first and second media, i is the angle of incidence, and r is the angle of refraction.

Answer

Given: i = 30°, r = 20°. Formula: n = sin i / sin r. Step 1: sin 30° = 0.5. Step 2: sin 20° ≈ 0.342. Step 3: n = 0.5 / 0.342 ≈ 1.46. Answer: refractive index ≈ 1.46.

Answer

When i = 0°, Snell's law gives r = 0°. So there is no bending of the ray at normal incidence.

Answer

n = c / v. Here c is the velocity of light in vacuum and v is the velocity of light in the medium. It has no unit and is greater than 1 for a material medium.

Answer

Given: n = 1.5, c = 3 × 10^8 m/s. Formula: n = c / v. Step 1: v = c / n. Step 2: v = (3 × 10^8 m/s) / 1.5 = 2 × 10^8 m/s. Answer: 2 × 10^8 m/s.