Nowadays optical fibers are extensively used for transmitting audio and video signals through long distances. The optical fibers work on
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Total internal reflection
An optical fibre has a core of higher refractive index surrounded by a cladding of lower refractive index. Light entering the core meets the core-cladding boundary at an angle greater than the critical angle, so it is totally reflected again and again and travels along the fibre with very little loss. This is total internal reflection.
NCERT (2026-27):
Total Internal Reflection in Nature and Its Technological Applications – “… (ii) Optical fibres: Nowadays optical fibres are extensively used for transmitting audio and video signals through long distances. Optical fibres too make use of the phenomenon of total internal reflection.”