Which of the following is used in optical fibres?
(a) Total internal reflection
(b) Scattering
(c) Diffraction
(d) Refraction

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Hint: The best way to solve the question is by using all basic information regarding optical fiber. The knowledge about reflection, refraction, scattering, and diffraction will also be enough for answering the question. Out of these four, the one having a property of capturing light in fiber will be the right answer.

Complete answer:
To answer this question we need to understand the fiber concept.

Optical Fiber: It is a type of fiber in which we will find a structure that is made with the help of glass or plastic. This type of structure is used for transmitting light. The fiber made by the glass or plastic results in the use of transmitting light. There are many fibers that are helpful in long-distance transmissions with higher bandwidths. The higher bandwidths result in the transmission of data. Since these do not include any type of metal in them, they give rise in the transference of the data without losing them.

The core is generally made up of glass or plastic. Since this core needs a kind of covering around it, a covering with usually a smaller refractive index than the core is always applied. If a beam of light is not trapped inside the fiber then it will result in no transmission. Because the less refractive index of the covering results into the core acting similar to a denser medium and the covering becomes the rarer medium.
Since, reflection is all about reflecting the light from, the surface that is why the total reflection internal of the fiber is used.

So, the correct answer is “Option A”.

Any fiber with a material made up of glass or silica instead of any metal in it implies a better transmission of information.
(1) There is a difference between reflection and refraction. The reflection reflects any form of light coming towards it whereas refraction lets the light pass through it.
(2) Diffraction is a wave phenomenon that detects the presence of bands like waves in the light.
(3) Scattering is a type of phenomenon in which light passing through any source of medium like air, or water, the process of slight absorption of light by the particles present in the medium results in the radiation of it in a particular direction.
Since all these properties are not needed in an optical fiber, this is why all the options except for the first one are discarded.