The working of an optical fiber is based primarily on the phenomenon of: MCQ with Answer and Explanation

Optical fibers consist of a central core surrounded by a cladding with a slightly lower refractive index. When a light beam enters the core at an angle greater than the critical angle, it undergoes multiple successive total internal reflections against the core-cladding boundary. This allows the light to travel over vast distances with virtually no loss of energy, making it ideal for telecommunications.