# Refraction of Light

## What is Refraction of Light in Ray Optics?

Refraction of light refers to the change in direction of a ray of light when it travels from one medium to another. For example, the figure below shows a ray of light traveling from a medium of air to that of water.

Have u ever soaked your legs in a bucket? You would have noticed that your legs looked slightly deformed and kind of shorter. The phase velocity of travelling light rays are altered when they travel from one medium to another of a different refractive index.

## What is Refractive Index?

Refractive Index is dimensionless. For a given material, the refractive index is the ratio between the speed of light in vacuum (c) and the speed of light in the medium (v). If the refractive index for a medium is represented by n, then it is given by the following formula.

$~~~~~~~$ $n = \frac {c}{v}$

Based on the refractive index of the medium, the light ray changes its direction, or it bends at the junction separating the two media. If the light ray travels from a medium to another of a higher refractive index, it bends towards the normal, else it bends away from the normal.

## Applications of Refraction of Light

Refraction has many applications in optics and technology. Depending on the type of spherical lens used (convex or concave) refraction through glass has many uses. Passing white light through a glass prism can split the white light into the spectrum of color (VIBGYOR). In nature, it is refraction that causes us to see different phenomenon like mirages and also the twinkling of stars… which is caused due to the atmospheric refraction of light.

Next time anyone asks you “Why do stars twinkle?”, you can say, “Because… Refraction of Light” Want to know more about the applications of refraction? Have fun while learning with BYJU’s.

#### Practise This Question

According to Snell's law, the value of the constant depends on :