Q14 of 29 Page 109

Coiled information a working of optical fibers. Prepare a report about various uses of optical rubles in our daily life. (AS4)

Optical fiber an optical fiber is a very thin fiber made up of glass or plastic having diameter about a micrometer (10-6 m). A bunch of such fibers form a light pipe.

Working Total internal reflection is the basic principle behind the working of the optical fibers. Because of the small radius of the fiber, light going into it makes a nearly Glancing incidence on the wall. The angle of incidence is greater than the Critical angle and hence total internal reflection takes place. The light is thus transmitted along the fiber. The figure below depicts the working of optical fibers..



Use of Optical fibers


1. Optical fibers are used in the medical equipment such as endoscope to observe deep parts of the body.


2. Optical fibers are used as sensors in industry to measure temperature and pressure.


3. They are used in telephones lines and internet cables for transmission.


More from this chapter

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12

Do activity-7again. How can you find critical angle of water? Explain your steps briefly. (AS3)

 13

Collect the values of refractive index of the following media. (AS4)

Water, coconut oil, flint glass, crown glass, diamond. benzene and hydrogen gas.

 15

Take a thin thermal sheet. Cut it in circular discs of different radii like 2cm, 3cm, 4cm, 4.5cm. 5cm etc ad mark centers with sketch pen. Now take needles of length nearly firm. Pin a needle to each disc at its centre vertically. Take water in a large opaque tray and place the disc with 2cm radius in such a way that the raw& is inside the water ac shown in fig Q15. Now try to view the free end (head) of the needle from surface of the water.


• Are you able to see the head of the needle?

 15

Take a thin thermal sheet. Cut it in circular discs of different radii like 2cm, 3cm, 4cm, 4.5cm. 5cm etc ad mark centers with sketch pen. Now take needles of length nearly firm. Pin a needle to each disc at its centre vertically. Take water in a large opaque tray and place the disc with 2cm radius in such a way that the raw& is inside the water ac shown in fig Q15. Now try to view the free end (head) of the needle from surface of the water.


• At what maximum radius of disc, were you not able to see the free end of the needle?