Question

In an optical fiber during transmission of light
(A) Energy increases
(B) Energy decreases
(C) No loss of propagation of energy takes place
(D) Light partially reflects and refracts.

Answer 1

Hint
Optical fibers are cables that carry information in the form of light pulses from one end of the fiber to another. It is made up of glass/quartz fibers. Each fiber consists of core and cladding. The refractive index of the core is higher than the cladding. It works on the phenomenon of total internal reflection. So, no refraction takes place in the transmission of light.

Complete step by step answer
When information in the form of light is passed through the optical fiber, it undergoes multiple reflections in a zig-zag motion and reaches the other end of the optical fiber.
Since only reflections are taking place and no amount of intensity of the light is lost in the propagation. Therefore, no loss of propagation of energy takes place.
Hence option (C) is correct.

Note
Data transmission in an optical fiber uses the phenomenon of total internal reflection. So, the light has to enter the optical fiber in an angle such that total internal reflection takes place inside the optical fiber. The refractive index of the core should be higher than the cladding because total internal reflection happens when light rays travel from an optically denser medium to an optically less dense medium and the angle of incidence of light should be equal to or greater than the critical angle. Critical angle depends upon the refractive indices of the materials.