Question

Explain, by ray diagram, how optical fibres transmit signals.

Answer 1

In the diagram, light enters the core of the optical fibre at an angle of incidence (i), and gets refracted at angle (r). Since the core (n₁) has a higher refractive index than the cladding (n₂), and the angle of incidence exceeds the critical angle, the light undergoes total internal reflection at the core-cladding boundary. This process repeats, allowing the light signal to travel along the fibre with minimal loss. The cladding keeps the light confined to the core by reflecting it back whenever it hits the boundary. Thus, the optical fibre transmits signals efficiently using the principle of total internal reflection.