Define refraction of light. State Snell's law of refraction of light.

Explanation

### Step-by-Step Text Solution:

**Step 1: Define Refraction of Light**
Refraction of light is the bending of light rays when they pass from one medium to another medium with a different optical density. This bending occurs because the speed of light changes as it moves between different materials. For example, when light travels from air (a rarer medium) into glass (a denser medium), it bends towards the normal line, which is an imaginary line perpendicular to the surface at the point of incidence.

**Step 2: Explain the Concept with a Diagram**
Imagine a light ray traveling in air that strikes the surface of a glass block. As it hits the glass, the light ray does not continue in a straight line; instead, it bends at the interface. The angle between the incident ray and the normal line is called the angle of incidence (denoted as \(i\)), and the angle between the refracted ray and the normal line is called the angle of refraction (denoted as \(r\)).

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