You must have seen that an object like pen bends in water! Do you know why? Let us discuss:

Every object has refractive index. Oh, do you know what is refractive index (n). It is the ratio of the speed of light in air (c) to speed of light in medium (v), that is

n = c/v

Origin of the term refractive index: Refractive comes from the word refraction that is “bending” and index from “point out” or “refer”. Thus refractive index signifies that how much light bends in a medium.

More the value of it, it means more the light bends in that medium.

For example, water has refractive index 1.33 and air has approximately 1. It means the light will bend more in water than air. Therefore the objects in water appears bended.

Glass has approximately 1.7 refractive index, so light will bend more in glass as compare to water.

Value of n can not be lesser than 1. Can you tell the answer, if yes, then please share your answer in the comment section.