Question

Swarali observed that the light bent away from the normal, while travelling from
ense medium to rarer medium. When Swarali increased the values of angle of
incidence (i), the values of angle of refraction (r) went on increasing. But at a
certain angle of incidence, the light rays returned into the dense medium.
So, Swarali has some questions. Answer them -
a) Name this certain value of 'i'. What is the value of 'r' at that time ?
b) Name this process of returning of light in dense medium. Explain the process.​

Answer 1

Answer:

a) The angle of incidence at which light reflects into the same medium rather than refracting into another medium is known as critical angle.

b) This process is known as Total Internal Reflection.

The process can be explained as follows-

1. When a light is incident on a surface obliquely, it refracts from the medium where it comes to the medium where it is going.
2. As we increase the angle of incidence, the angle of refraction also increases
3. At a time when the angle of incidence is such that that the refracted ray does not refract, but it gets reflected back in the same medium.
4. This phenomena is known as Total Internal Reflection.