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प्रश्न
Describe the construction and working of an optical fibre.
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उत्तर
Construction:
- An optical fibre consists of an extremely thin, transparent, and flexible core surrounded by an optically rarer flexible cover called cladding.
- For protection, the whole system is coated by a buffer and a jacket
- The entire thickness of the fibre is less than half an mm.
- Many such fibres can be packed together in an outer cover.
Construction of Optical fiber
Working:
- Working of optical fibre is based on the principle of total internal reflection.
- An optical signal (a ray of light) entering the core suffers multiple total internal reflections before emerging out after several kilometres.
- The optical signal travels with the highest possible speed in the material.
- The emerged optical signal has an extremely low loss in signal strength.
Working of Optical fibre
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संबंधित प्रश्न
State the conditions required for total internal reflection of light to take place
State the relation between the critical angle and the absolute refractive index of a medium.
Draw the diagram of a right-angled isosceles prism which is used to make an invented image erect.
What do you understand by the deviation produced by a prism? Why is it caused?
Name two factors which affect the critical angle for a given pair of media. State how do the factors affect it.
State two conditions necessary for total internal reflection to occur.
Draw diagram to illustrate the total internal reflection.
In the given figure PQ and PR are the two light rays emerging from an object P. The ray PQ is refracted as QS.
- State the special name given to the angle of incidence ∠PQN of the ray PQ.
- What is the angle of refraction for the refracted ray QS?
- Name the phenomenon that occurs if the angle of incidence ∠PQN is increased.
- The ray PR suffers partial reflection and refraction on the water-air surface. Give reason.
- Draw in the diagram the refracted ray for the incident ray PR and hence show the position of image of the object P by the letter P’ when seen vertically from above.
Two isosceles right-angle glass prisms P and Q are placed near each other as shown in Fig. Complete the path of the light ray entering the prism P till it emerges out of the prism Q.
Plot a graph between
Angle of incidence versus angle of refraction.
(a) A ray of monochromatic light enters glass PQRS as shown in the fig. Complete the path of ray till it emerges from the glass. (Critical angle of glass is 420).
(b) Draw diagram of a prism periscope.
(c) What are the advantages of total internal reflecting prism over plane mirror?
Write down the relationship between the critical angle and the refractive index of the medium.
Express the refractive index μ of a medium in terms of the angle of incidence i in air and the angle of refraction r in a denser medium.
How are critical angles related to the refractive index of the medium?
State two advantages of using a right-angle prism as a reflector, rather than a plane mirror.
How is the critical angle of a material related to its refractive index?
Complete the following diagram to show the path of the ray of a single colour in the diagram as if enters in and emerges out of the prism. Mark the angles wherever necessary. (Critical angle for glass = 42°).
Which of the following is not involved in formation of a rainbow?
Answer the following question.
What are the advantages of optical fibre communication over electronic communication?
For the same angle of incidence, the angle of refraction in four media A, B, C and D are 25°, 30°, 35° and 40° respectively. The speed of light is least in medium ______.
For total internal reflection to take place, the angle of inddence i and the refractive index µ of the medium must satisfy the inequality ____________.
For a ray of light, the critical angle is minimum when it travels from ______.
The entire light is reflected back into the denser medium is called ______.
The angle of incidence at which the angle of refraction is Q£ is called the critical angle.
What is a mirage? How does it occur?
What is the phenomenon used in optical fiber? Explain.
The angle made by incident ray of light with normal of the reflecting surface is called ______.
- Assertion (A): Propagation of light through an optical fibre is due to total internal reflection taking place at the core-cladding interface.
- Reason (R): Refractive index of the material of the cladding of the optical fibre is greater than that of the core.
Small air bubbles rising up a fish tank appear silvery when viewed from some particular angle is due to the ______.
