Total internal reflection of light.

This is the phenomenon which is observed when the light light is transmitted from denser medium to rarer medium and the reflected light is completely reflected in the first medium when the angle of incidence is greater than Critical Angle C.

 when the  light is transmitted from denser medium to rarer medium the refracted light bends away from the normal in the second medium. 

The angle of refraction is greater than that of the angle of incidence.

 By increasing the angle of incidence the angle of refraction is also increased.  It is observed that at an angle of incidence the angle of refraction is exactly 90 degrees.

 This angle of incidence where the angle of reflection is exactly  90° is defined as Critical Angle ‘C’. 

The value of angle depends upon the material of the medium.

 further increase in angle of incidence the angle of refraction is greater than  90° and then the reflected light is completely reflected into the first medium instead of  transmitting into the second medium.

                                

Applications of total internal reflection

1. There are some natural applications of total internal reflection in the formation of optical illusions Like mirages,  rainbow rainbow  and sparkling of diamonds.

2. In communication systems optical fibers work on the principle of total internal reflection only. 

 The communication signals are converted into optical signals and sent through the cables which are made of optical fibres.

 

3.The working of periscope is based on total internal reflection of light.