# Learning Elementary Physics for Class 8: Physics - Unit 3 - Refraction of light Flashcards

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Physics, Science. Part of PT-3
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1

Define refraction of light.

The phenomenon due to which a ray of light deviates from its path, at the surface of separation of two optical media, when the ray of light is travelling from one optical medium to another medium is called refraction of light.

2

What are the 3 rules for the deviation of rays in another optical medium?

1. When a ray of light travels from air to glass, it bends towards the normal at the surface of the separation of two media.
2. When a ray of light travels from glass to air, it bends away from the normal at the surface of the separation of two media.
3. When a ray of light strikes the surface of separation of two media at an angle of 90o it does not deviate from its path.
3

What is an incident ray and point of incidence?

A ray that strikes the surface of separation of two optical media is known as an incident ray.

The point of the surface of separation of two optical media, where the incident ray strikes is known as the point of incidence.

4

What is a refracted ray and angle of refraction?

A ray that travels in the second optical medium, with the change of angle of the incident ray is known as a refracted ray.

The angle which a refracted ray makes with the normal, at the point of incidence, is known as the angle of refraction.

5

What are the 2 laws of refraction?

1. The incident ray, the normal, and the point of refraction all lie in the same plane.
2. The ratio of perpendicular in the air to the ratio of perpendicular in the denser medium is a constant quantity and commonly called refractive index of the denser medium
6

What is the relation between the velocity of light in various media?

The ratio between the velocity of light in vacuum or air to the velocity of light in an optically denser medium is called the refractive index of the denser medium.

7

What is the formula for refractive index of glass?

Velocity of light in air or vacuum= 3 x 108 ms-1

__________________________________________________________________ = 1.5

Velocity of light in glass= 2 x 108 ms-1