Question

A ray of light enters a glass slab PQRS as shown in the diagram. The critical angle of glass is 42°. Copy the following diagram and complete the path of the ray till it emerges from the glass slab. Mark the angles in the diagram wherever necessary.

Answer 1

The critical angle of glass is 42°. At surface PQ, the angle of incidence is 45°, which is greater than the critical angle (45° > 42°), causing Total Internal Reflection (TIR). The ray then suffers another TIR at surface PS at 45° and emerges normally from the curved surface without deviation.