# Refraction Introduction and Laws of Refraction | Physics Grade XI

### Refraction

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#### Kinematics

Introduction to Kinematics

# Refraction Introduction and Laws of Refraction

Refraction
Light travels in a straight line in one medium. When it changes medium it bends. So, the phenomenon of bending of light when it passes from one medium to another is called refraction.

Laws of refraction

1. The incident ray, refracted ray, and normal at the point of the incident all lie in the same plane.
2. When light travels from rarer medium to denser medium, it bends towards the normal and when light travels from denser medium to rarer medium, it bends away from normal.
3. When given two media, the ratio of sine of the angle of incidence to the sine of the angle of refraction is constant, called refractive index and is denoted by µ.

i.e. µ = sin i / sin r, this is also called Snell’s law.

Fig: Refraction of light from air to glass

Here, AO is the incident ray falling in the surface and,
aµg = sin i / sin r and,
gµa = sin r / sin i

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