Total internal reflection can occur only when light passes from a material of high refractive index to one of low refractive index,never the other way around.

Question

Quizplus · Accepted Answer

Total internal reflection occurs when light passes from a material of high refractive index to one of low refractive index at an angle greater than the critical angle. This is because the light is unable to bend enough to pass through the boundary and is instead reflected back into the higher refractive index material. If light passes from a material of low refractive index to one of high refractive index, it bends towards the normal and there is no possibility of total internal reflection occurring.

Total Internal Reflection Can Occur Only When Light Passes from a Material