Question

# For a total internal reflection, which of the following is correct?A. Light travels from rarer to denser mediumB. Light travels from denser to rarer mediumC. Light travels in air onlyD. Light travels in water only

Hint: When light travels from an optically denser to an optically rarer medium, the angle of refraction is greater than the angle of incidence and keeps on increasing as the angle of incidence is increased.

Complete step by step answer:
Total Internal reflection (TIR) is the phenomenon in which light travels from an optically denser to an optically rarer medium but is reflected back into the denser medium at the interface.

This happens when the angle of incidence passes a certain angle known as the

Critical angle (θc). The critical angle is given by
${{\theta }_{c}}={{\sin }^{-1}}\dfrac{{{\mu }_{1}}}{{{\mu }_{2}}}$

Where 1 and 2 are the optical densities or refractive indices of the optically rarer and optically denser medium respectively.

In this case the whole of the incident ray is completely reflected back into the medium i.e. 100%. There is no refracted ray.