Refraction of Light by 2E1 Lee Jae Woong

Refraction
Through our project, I have learnt about refraction and its uses. Refraction refers to the bending of light as it passes between materials of different optical density.

In refraction, I learnt that the denser the material is, the slower the speed of light will be in that material. Refraction will happen when light passes from one medium to another medium with different densities.

For example, when light passes from air to a transparent glass block, the speed of light will slow down and it will cause the light ay to bend closer to the normal.

As seen in diagram 1, the light ray passes from air to a transparent glass block. The light ray, as shown, is bent towards the normal. This indicates that the speed of light is reduced when passing from one medium to another. The denser the medium is, the light ray will bend closer towards the normal. Similarly, when the light ray moves from glass block to air it is refracted away from the normal

Refractive Index
The refractive index of a medium is the measurement of how much the speed of light has reduced or increased inside various types of medium. Generally, the refractive index is subject to changes based on the incidence of the light. This explains why different colours of light travel at different speeds. The higher the index, the slower the speed of light will be through the medium.

Formula for refractive Index is n= sin i / sin r

Effects of Refraction
Effects of refraction can be seen in our everyday lives.

Firstly, refraction causes objects to appear closer than it actually is. For example, in a swimming pool, the pool looks shallower than it actually is. This is because our brains think the light has moved in a straight line. Therefore the swimming pool seems shallower than it usually is. Another example, is when we place our hand below a glass block, our hand seems nearer to the surface than it is. Thus the glass block seems thinner than the actual thickness.

As seen in diagram 2 the pool seems to be of equal depth and it looks shallow. However it is actually deeper than it looks. Due to refraction, swimming pools or ponds always appear to be shallower than they really are. When approaching air from water, the waves speed up and as a result they refract away from the normal.

Diverging rays enter the eye and the brain traces these rays back to where it thinks an image is. This results in a virtual image at a shallower depth than is the actual case.

References
1. Refraction of Light by Rick Reed http://www.ps.missouri.edu/rickspage/refract/refraction.html
2. Explore your world with Science Discovery 2 Textbook
3. Answers.Com http://www.answers.com/topic/refractive-index?cat=technology
4. http://www.asiatravel.com/turkey/istanbul/marinprincesskumburgaz/gifs/pool2.jpg
5. http://pachome2.pacific.net.sg/~ezzychan/refraction.htm