Total internal reflection
Total internal reflection
When the angle of incidence is greater than the critical angle, the light ray gets reflected into the denser medium at the interface i.e., light never enters the rarer medium. This phenomenon is called total internal reflection.
Applications of total internal reflection:
1.Brilliance of Diamonds : Total internal reflection is the main reason for brilliance of diamonds. The critical angle of a diamond is very low(22.4). So, if a light ray enters a diamond it is very likely to undergo total internal reflection which makes the diamond shine.
2.Optical fibres : Total internal reflection is the basic principle behind working of optical fibre. An optical fibre is a thin fibre made of glass (or) plastic having radius about a micrometre. A bunch of such thin fibres form a light pipe.
Because of the small radius of the fibre, light going into it makes a nearly glancing incidence on the wall. The angle of icidence is greater than the critical angle and hence total internal reflection takes place. The light is thus transmitted along the fibre.
All organs of the body are not accessible to the naked eye of the doctor, for example intestines. The doctor inserts an optical fibre pipe into the stomach through the mouth. Light is sent down through one set of fibres in the pipe. This illuminates the inside of the stomach.The light from the inside travels back through another set of fibres in the pipe and the viewer gets the image at the outer end.
The other important application of fiber optics is to transmit communication signals through light pipes. Foe example, 2000 telephone signals, appropriately mixed with light waves, may be simultaneously transmitted through a typical optical fibre. The clarity of the signals transmitted in this way is much better than our conventional methods.
This is about the Total internal reflection and it's applications.
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