What is Total Internal Reflection ?

 Total Internal Reflection

• When the light goes from a denser to a rarer medium it bends away from the normal.

• The angle at which the incident ray causes the refracted ray to go along the surface of the two media parallelly is called Critical Angle.
  

• Refractive Index of one medium with respect to another medium is called Relative Refractive Index.

• When Refractive Index is taken with respect to vacuum or air, it’s known as an Absolute Refractive Index.

• Optically denser medium: Out of two given media, the medium with higher value of refractive index.

•  Optically rarer medium: Out of two given media, the medium with lower value to refractive index.

When light enters obliquely from a rarer to a denser medium, it bends towards the normal.

When light enters obliquely from denser to a rarer medium, it bends away from the normal.

When the incident angle is greater than the critical angle, it reflects inside the denser medium instead of refracting. This phenomenon is known as Total Internal Reflection.