For a total internal reflection, which of the following is correct?

Light travels from denser to rarer medium.

The correct answer is Option 2: Light travels from denser to rarer medium.

Total internal reflection occurs when light travels from an optically denser medium to an optically rarer medium and the angle of incidence is greater than the critical angle. In such a case, the light is completely reflected back into the denser medium.

Option 1: Light travels from rarer to denser medium. In this case, total internal reflection cannot occur because the light bends towards the normal instead of getting completely reflected.

Option 3: Light travels in air only. Total internal reflection is not restricted to air. It depends on the change of medium and angle of incidence.

Option 4: Light travels in water only. Total internal reflection is not limited to water. It can occur in many transparent media such as glass, water, and optical fibres.