NTA Abhyas 2020
- Exam
- NTA Abhyas
- Year
- 2020
- Subject
- Physics
- Chapter
- Communication System
NTA Abhyas 2020 · Physics · Communication System
Consider telecommunication through optical fibres. Which of the...
Consider telecommunication through optical fibres. Which of the following statements is not true?
Options
- Aoptical fibres can be of graded refractive index
- Boptical fibres are subjected to electro-magnetic interference from outside
- Coptical fibres have extremely low transmission loss
- Doptical fibres may have homogeneous core with a suitable cladding
Correct answer
B. optical fibres are subjected to electro-magnetic interference from outside
Step-by-step solution
Some of the characteristics of an optical fibre are as follows.
(i) This works on the principle of total internal reflection.
(ii) It consists of core made up of glass/silica/plastic with refractive index which is surrounded by a glass or plastic cladding with refractive index {n}_{2}\left({n}_{2} > {n}_{1}\right). The refractive index of cladding can be either changing abruptly or gradually changing (Graded index fibre).
(iii) There is a very little transmission loss through optical fibres.
(iv) There is no interference from stray electric and magnetic fields to the signals through optical fibres.