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Directions (Q. No. 11 to 15):

Read the following text and answer the following questions on the basis of the same:

Optical Fibre:

Optical fibre works on the principle of total internal reflection. Light rays can be used to transmit a huge amount of data, but there is a problem here - the light rays travel in straight lines. So unless we have a long straight wire without any bends at all, harnessing this advantage will be very tedious.

Instead, the optical cables are designed such that they bend all the light rays' inwards (using TIR).

Light rays travel continuously, bouncing off the optical fibre walls and transmitting end to end data. It is usually made of plastic or glass.

Modes of transmission: Single-mode fibre is used for long-distance transmission, while multi- mode fiber is used for shorter distances. The outer cladding of these fibres needs better protection than metal wires. Although light signals do degrade over progressing distances due to absorption and scattering. Then, optical Regenerator system is necessary to boost the signal.

Types of Optical Fibres: The types of optical fibers depend on the refractive index, materials used, and mode of propagation of light. The classification based on the refractive index is as follows:

• Step Index Fibres: It consists of a core surrounded by the cladding, which has a single uniform index of refraction.

•  Graded Index Fibres: The refractive index of the optical fibre decreases as the radial distance from the fibre axis increases.

Optical fibre works on the principle of:

A) scattering of light.

B) diffraction of light.

C) total internal reflection of light.

D) dispersion of light.