In refraction of light, `( sin i)/(sin r )`= constant in a particular case. What is this constant called?

Explanation

To solve the question, we need to understand the relationship between the angles of incidence and refraction when light passes from one medium to another. The relationship is described by Snell's Law, which states that the ratio of the sine of the angle of incidence (i) to the sine of the angle of refraction (r) is a constant for a given pair of media.

### Step-by-Step Solution:

1. **Understanding Refraction**: When light travels from one medium to another (for example, from air to glass), it changes speed, which causes it to change direction. This phenomenon is known as refraction.

2. **Defining the Angles**:
- The angle of incidence (i) is the angle between the incident ray and the normal (an imaginary line perpendicular to the surface at the point of incidence).
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