Total Internal Reflaction : When light passes from an optically denser medium to a rarer medium at the interface, under certain conditions the incident light can be made to be reflected back into the same medium without any loss of intensity.This pheomenon is called Total Internal Reflaction.
Essential Conditions :
(i) Light should travel from a denser medium to a rarer medium.
(ii) Angle of incidence in densor medium should be greater than the critical angle for the pair of media in contact.