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प्रश्न
Answer the following question.
What are the advantages of optical fibre communication over electronic communication?
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उत्तर
Advantages:
- Broad bandwidth (frequency range): For TV signals, a single optical fibre can carry over 90000 independent signals (channels).
- Immune to EM interference: Optical fibre being electrically non-conductive, does not pick up nearby EM signals.
- Low attenuation loss: loss being lower than 0.2 dB/km, a single long cable can be used for several kilometres.
- Electrical insulator: Optical fibres being electrical insulators, ground loops of metal wires or lightning do not cause any harm.
- Theft prevention: Optical fibres do not use copper or other expensive material which are prone to be robbed.
- Security of information: Internal damage is most unlikely to occur, keeping the information secure.
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संबंधित प्रश्न
A ray of light travels from water to air as shown in the diagram given below :
1) Copy the diagram and complete the path of the way. Given the critical angle for water is 48°.
2) State the condition so that internal reflection occurs in the above diagram.
The figure shows a ray of light falling normally on the face AB of an equilateral glass prism having refractive index`3/2`, placed in water of refractive index `4/3`.Will this ray suffer total internal reflection on striking the face AC? Justify your answer.
Which colour of light has a higher critical angle? Red light or green light.
What do you understand by the deviation produced by a prism? Why is it caused?
Write the necessary conditions for the phenomenon of total internal reflection to
occur ?
Write the relation between the refractive index and critical angle for a given pair of optical media?
One day Chetan’s mother developed a severe stomach ache all of a sudden. She was rushed to the doctor who suggested for an immediate endoscopy test and gave an estimate of expenditure for the same. Chetan immediately contacted his class teacher and shared the information with her. The class teacher arranged for the money and rushed to the hospital. On realizing that Chetan belonged to a below average income group family, even the doctor offered concession for the test fee. The test was conducted successfully.
Answer the following questions based on the above information:
(a) Which principle in optics is made use of in endoscopy?
(b) Briefly explain the values reflected in the action taken by the teacher.
(c) In what way do you appreciate the response of the doctor on the given situation?
Prove the statement.
A rainbow is the combined effect of the refraction, dispersion, and total internal reflection of light.
(i) Define critical angle.
(ii) State one important factor which affects the critical angle of a given medium.
(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?
How does a ray of light bend when it travels from denser to rarer medium.
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’.
What can you say about the value of the angle of deviation in such a situation?
Draw a diagram, properly labelled, to illustrate the use of a total reflecting prism (a right-angled isosceles prism) to turn a ray of light through 180°. Name an instrument in which this device is used.
The diagram shows a point source P inside a water container. Three rays A, B, and C starting from P are shown up to the water surface. Show in the diagram the path of these rays after striking the water surface. The critical angle for the water-air pair is 48°.
The adjacent diagram shows two right-angled isosceles prisms A and B. Complete the diagram to show the path of rays P and Q emerging out of the prism B. What principles have you used to complete the diagram?
Describe the construction and working of an optical fibre.
The angle of minimum deviation produced by a thin glass prism in air is 'δ'. If that prism is immersed in water, the angle of minimum deviation will be ______.
( aμg = refractive index of glass w.r.t, air aμw = refractive index of water w.r.t. air)
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 bundle of glass threads, each of which is capable of transmitting messages using light waves is called ______.
Which of the following statements about total internal reflection is true?
Write any two uses of total internal reflection.
Observe the given figure of the raindrop and answer the following questions:
- Label A and B of the given diagram. Why colour will deviate most.
- Name the phenomenon shown in label C.
- 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.
When a ray of light is refracted from one medium to another, then the wavelength changes from 6000 Å to 4000 Å. The critical angle for the interface will be ______.
