Refraction is the bending of a wave when it passes from one medium to another. The bending is caused due to the differences in density between the two substances.
Defining Refraction
“Refraction is the change in the direction of a wave passing from one medium to another.”
Refraction of light is one of the most commonly observed phenomena, but other waves like sound waves and water waves also experience refraction. Refraction makes it possible for us to have optical instruments such as magnifying glasses, lenses and prisms. It is also because of the refraction of light that we are able to focus light on our retina.
Did you know that the twinkling effect of stars is due to atmospheric refraction? The starlight undergoes several refractions while reaching the Earth. This atmospheric refraction occurs in a medium of gradually changing refractive index.