Research on Applications of Total Internal Reflection (TIR)

These are the Uses and Applications of Total Internal Reflection that I had researched on:

1) Can be used to make diamonds sparkle (because of the reflection then we can see the diamond sparkle)

- The cut or shape of a diamond is nicely 'suited' for total internal reflection. Light Rays which enter the diamond from one of its 5 sides (for a 2D Shape Diamond) will therefore be nicely reflected back out from the same side which they entered the diamond. There will hence not be any refracted ray when a light ray enters a diamond, basically due to its shape. What causes the diamond to sparkle is the way the light ray enters and leaves the diamonds, where they will enter and leave from the same side of the diamond. 

2) Can be used to let information travel rapidly on light waves through a fiber optic

- A fiber optic is a glass 'hair' which is so thin that once light enters it from one end, it can never strike the inside walls less than the critical angle. Therefore, the light rays will have to undergo total internal reflection in the fiber optics each time it strikes the walls in them, before it actually exits the fiber when it reaches the other end. Fibre optic cables are used to carry telephone and computer communications. This is why total internal reflection is so important, because it helps us to be able to communicate with others.

3) Will Occur in Deserts on Hot Summer Days. Mirage is an optical illusion.

- In deserts, the temperature of air near the earth is maximum and hence is rarer or lighter. The upper layers of air, which is cooler, will be denser. A ray of light from the top of a tree in the desert will travel from denser air to rarer air and eventually bend away from the normal. At a particular layer, if the angle of incidence were to be greater than the critical angle, then total internal reflection will occur. Thus, the inverted image of this tree will create an optical illusion of reflection from a pond of water. Having total internal reflection is also why we are able to see the reflection of a tree in a pond of water in deserts.

Sources: http://regentsprep.org/Regents/physics/phys04/captotint/default.htm
http://www.tutorvista.com/content/physics/physics-iv/optics/total-internal-reflection.php 

Done By: Tan Hao Ming (18)