Refraction of light

Priyanka Devan
Updated on

Refraction of Light

The refraction of light is the bending of a wave as it passes from one medium to another. It signifies a change in the velocity (speed) of the wave. It is also the bending of light as it passes from one transparent substance into another. Refraction of light is the most commonly observed phenomenon, but other waves such as sound waves and water waves also experience refraction.

This bending by refraction makes it possible for us to have lenses, magnifying glasses, prisms and rainbows. Even our eyes depend upon this bending of light. Without refraction, we wouldn’t be able to focus light onto our retinas.

Examples of refraction of light:

  • Twinkling of stars in a clear sky.
  • Pool of water appears to be less deep than what it actually is.
  • Rainbow formation in the sky.
  • Glasses or Contacts. You might not realize it, but if you wear glasses or contact lenses, this is light refraction at play. 
  • Human Eyes. Human eyes have a lens. 
  • Prism. 
  • Pickle Jar. 
  • Ice Crystals. 
  • Glass.
  • Microscope or Telescope

What causes refraction?

The cause of the refraction of light is that light travels at different speeds in different media. This change in the speed of light when it moves from one medium to another causes it to bend.

Refraction is caused due to the change in speed of light when it enters from one medium to another.

  1. When the light goes from air into water, it bends towards the normal because there is a reduction in its speed.
  2. When the light goes from water to air, it bends away from the normal because three increases the speed of light.

Types of Refraction

  • Refraction from denser to the rarer medium: In this case, the relative refractive index is less than 1. Here the angle of incidence is less than the angle of refraction, that is the refracted ray is 10 to shift away from the normal. For example The refraction from glass to air. 
  • Refraction from rarer to the denser medium: In this case, the relative refractive index is greater than 1. Here the angle of incidence is greater than the angle of refraction. Thus, the refracted ray tends to shift towards the normal. For example: The refraction of light in water from the air.

Check your knowledge

  • Prism. A glass prism is an instrument that is capable of demonstrating the refraction property of light in one of the easiest possible manners. 
  • Ice Crystals. 
  • Glass. 
  • Twinkling of Stars. 
  • Lens.
Two things change when light goes from one medium to another: the speed of the light and thewavelength of the light. But the frequency of the series of the light waves, passing a given point per second, does not change; thus the color does not change.

If the refractive indices are same in both medias then there will be no refraction and light will pass without any refraction. And when the incident ray is striking perpendicular to one media to another the light will pass without any refraction.

In Optics, The angle of incidence to which the angle of refraction is 90° is called the critical angle.

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