UPSC 2016 CDS II GK Paper

In total internal reflection, the light travels from the denser to the rarer medium and it occurs with no loss of intensity. When the angle of incidence is greater than 48.6 degrees (the critical angle), all of the energy (the total energy) carried by the incident wave to the boundary stays internal to the original medium and undergoes reflection off the boundary. When this happens, total internal reflection occurs.