11. Total Internal Reflection

 

Johannes Kepler

In 1611, Johannes Kepler, a German mathematician and astronomer, discovered the phenomenon of total internal reflection.Total Internal Reflection is a phenomenon that makes us to feel the water-to-air surface in a fish tank look like a perfectly silvered mirror when we viewed from below the water level. The complete reflection of a light ray reaching an interface with a less dense medium when the angle of incidence exceeds the critical angle. The critical angle is the smallest angle of incidence that yields total internal reflection, that means it is the angle of incidence at which the angle of refraction reaches the value of 90^o . Hence there are two conditions for total internal reflection to takes place and they are :-

>> Angle of incidence should be greater than the critical angle (i_c) .

>> Ray should travel from denser medium to rarer medium.

  

This is the technique used in the optical fibers technology and it is also the reason for the shining of diamond stones.