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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
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.
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.
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.
Prove the statement.
A rainbow is the combined effect of the refraction, dispersion, and total internal reflection of light.
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.
Solve the previous problem if the paperweight is inverted at its place so that the spherical surface touches the paper.
Define critical angle for a given medium.
Plot a graph between
Angle of incidence versus angle of reflection,
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.
If a ray of light passes from medium I to medium II without any change of direction, what can be said about the refractive indices of these media (angle I is not 0)?
How are critical angles related to the refractive index of the medium?
Name the factors affecting the critical angle for the pair of media.
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.
Choose the correct option.
Consider the following phenomena/ applications: P) Mirage, Q) rainbow, R) Optical fibre and S) glittering of a diamond. Total internal reflection is involved in
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?
Describe the construction and working of an optical fibre.
For total internal reflection to take place, the angle of inddence i and the refractive index µ of the medium must satisfy the inequality ____________.
The entire light is reflected back into the denser medium is called ______.
A bundle of glass threads, each of which is capable of transmitting messages using light waves is called ______.
Write any two uses of total internal reflection.
A green light is incident from the water to the air-water interface at the critical angle (θ). Select the correct statement.
A rectangular block of glass ABCD has a refractive index 1.6. A pin is placed midway on the face AB (Figure). When observed from the face AD, the pin shall ______.
- appear to be near A.
- appear to be near D.
- appear to be at the centre of AD.
- not be seen at all.
A ray of light passes through a prism of refractive index `sqrt2` as shown in the figure. Find:
- The angle of incidence (∠r2) at face AC.
- The angle of minimum deviation for this prism.
The angle made by incident ray of light with normal of the reflecting surface is called ______.
Name any two phenomena which take place in the formation of a rainbow.
