Question

(a) State and explain the laws of refraction of light with the help of a labelled diagram.
(b) What is meant by the refractive index of a substance?
(c) Light travels through air at 300 million ms−1. On entering water it slows down to 225 million ms−1. Calculate the refractive index of water.

Answer 1

Explanation:

(a) Laws of Refraction:

Law 1: The incident ray, the normal and the refracted ray, all must lie on the same plane.

Law 2: The ratio between the sine of the angle of incidence and sine of the angle of refraction is constant for any two medium.

(b) The refractive index of a substance is defined as a ratio between the velocity of light in a vacuum and velocity in a specific substance.

i.e., refractive index, n = $\frac{\text {Velocity of tight in vacuumm}}{\text {Velocity in a specific substance}}=\frac{c}{v}$

(c) From the question,

Speed of light in air = 300 million m/s

Speed of light in water = 225 million m/s

Now, the refractive index of water, nwater = $\frac{\text { Speed of light in air }}{\text { Speed of light in water }}=\frac{300 \text { million } \mathrm{m} / \mathrm{s}}{225 \text { million } \mathrm{m} / \mathrm{s}}$

  nwater = 1.33.

You can get all the answers of Chapter 5 in the link below:

https://brainly.in/question/14963222

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