Advertisements
Advertisements
प्रश्न
Describe the construction and working of an optical fibre.
Advertisements
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
APPEARS IN
संबंधित प्रश्न
You are given prisms made of crown glass and flint glass with a wide variety of angles. Suggest a combination of prisms which will
(a) deviate a pencil of white light without much dispersion,
(b) disperse (and displace) a pencil of white light without much deviation.
State the conditions required for total internal reflection of light to take place
Name the factors affecting the critical angle for the pair of media.
Total internal reflection occurs only when a ray of light passes from a ______ medium to a ______ medium.
Write the necessary conditions for the phenomenon of total internal reflection to
occur ?
Calculate the speed of light in a medium whose critical angle is 30° ?
Swarali has got the following observations while doing an experiment. Answer her questions with the help of observations.
Swarali observed that the light bent away from the normal, while travelling from dense medium to rarer medium. When Swarali increased the values of angle of incidence (i), the values of angle of refraction (r) went on increasing. But at a certain angle of incidence, the light rays returned into the dense medium.
So, Swarali has some questions. Answer them –
a) Name this certain value of ‘i ’. What is the value of ‘r’ at that time ?
b) Name this process of returning of light in dense medium. Explain the process.
Plot a graph between
Angle of incidence versus angle of reflection,
If a light ray does not undergo, refraction at the boundary between two media, the angle of incidence is:
(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?
Make the correct choices for each of the following :
Total Internal reflection takes place when
(where ∠i = angle of incidence, ∠r = angle of refraction, ∠C = critical angle)
Images formed by totally reflecting prisms are brighter than the image formed by ordinary reflected light, why?
A ray of light incident at an angle of incidence ‘i’ passes through an equilateral glass prism such that the refracted ray inside the prism is parallel to its base and emerges from the prism at an angle of emergence ‘e’.
How is the angle of emergence ‘e’ related to the angle of incidence ‘i’?
A ray of light passes through a right-angled prism as shown in the figure. State the angles of incidence at the faces AC and BC.
A spherical marble, of refractive index 1.5 and curvature 1.5 cm, contains a tiny air bubble at its centre. Where will it appear when seen from outside?
Solve Numerical example.
A monochromatic ray of light is incident at 37° on an equilateral prism of refractive index 3/2. Determine angle of emergence and angle of deviation. If angle of prism is adjustable, what should its value be for emergent rays to be just possible for the same angle of incidence?
Which one of the following is NOT the correct formula for refractive index of glass w.r.t. air (aμg) (i = angle of incidence, r = angle of refraction)
Total internal reflection can take place only if light is travelling from ______.
A particle is projected such that the horizontal range and vertical height are equal. Then the angle of projection is :
A green light is incident from the water to the air-water interface at the critical angle (θ). Select the correct statement.
The phenomena involved in the reflection of radiowaves by ionosphere is similar to ______.
A light is entering from one medium refractive index `("RI" =5/3)` to another medium at an angle 30°. The angle of refraction for other medium is sin-1 `(5/6)`. then the increase in angle of incidence is ______ such that the ray of light reflected back into the same medium.
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 ______.
