Refraction of Light by 2E1 The Su Zin

After doing research about this topic, I have learnt more concerning with the topic: refraction such as its laws and rules and also about refractive index.

1)Refraction
Refraction refers to the change in direction of light when it moves from one transparent medium into another transparent material which causes it to travel at a different speed.

Light slows down

Visible light is electromagnetic radiation or waveform. The speed or velocity of light in a vacuum is about 186,000 miles per second or 300,000 kilometres per second. The velocity of light or other electromagnetic radiation is typically slower when it passes through a transparent material. For example, the speed of light in water is about 140,000 mi/sec or 226,000 km/sec.

2)Refraction Rules When visible light passes through a transparent material such as glass and water, its velocity(speed) changes according to the index of refraction of the material. The index of refraction of air is about 1.00 and that of water is 1.33. When the beam of light enters water at an angle, it is bent or refracted as a result of the decrease in velocity.
Light is refracted inward when entering medium of higher index of refraction
Light is refracted outward when entering medium of lower index of refraction
The bending occurs because light travels more slowly in a denser medium.

Why does the light beam bend?
Considering a group of soldiers marching into a muddy field at an angle to their direction of travel can explain how a beam of light will be refracted. As the soldiers try to stay in a line, the direction of travel would bend because marching in mud would slow them down, starting with the first group to enter the field. Then, as they leave the muddy area, they go to their original speed, thus bending the direction of travel again. The original direction and the final direction are parallel but displaced.
The same thing happens when a beam of light enters a transparent material at an angle.

Example of how light is refracted when passes through different medium.

3 )INDEX OF REFRACTION
Refractive index is a number which indicates the power of refraction of a given medium relative to a previous medium. The absolute refractive index of a medium is the speed of light in a vacuum (air) divided by the speed of light in that medium.
Symbol is “n”. The larger the index ,the smaller the speed of light.
n = c/v

4)THE EFFECTS OF REFRACTION
Refraction has some unusual effects in everyday life.
-When a submerged object is viewed from above the surface of water, it appears closer to the surface than it is. This is due to light rays from the object being bent away from the normal as they pass out of the water (the more dense medium) into air (the less dense medium).
-The ratio of the real depth of the object to its apparent depth equals the refractive index of water.

Here are some examples of the EFFECTS:

eg1 - Apparent Depth in Water
In the above diagram, the chest seems to be nearer to the surface, but it is not. Refraction causes the chest to appear nearer to the surface than it actually is when it is in transparent material, water .

When you look at something under the water, not only the position of the object is not located at the place you though it was. The shape of the object is also changed. Location of the image and its shape are all depend on the location you view it.

eg2- In this diagram, the straw seems bent in the glass.
Refraction causes point X to appear nearer to the surface at Y so we see that that the straw appears to bend nearer to the surface of the water. This is one of the effect of refraction.

Eg.3 Pencil in water glass

You can also see this effect by putting a pencil in a glass of water. It appears as if the pencil is broken, but it is just because of the refraction of light.
The light from the pencil is refracted as it passes from the water to the glass to air, causing it to be displaced. Since the surface of the glass is curved, the water in the glass also acts as a magnifying glass, slightly enlarging the pencil.

So here is the link for mini short quiz, very simple quiz. =)
http://www.school-for-champions.com/science/light_refraction.htm#Mini-quiz

Acknowledgement
1 . http://sol.sci.uop.edu/~jfalward/refraction/refraction.html
2.http://sg.answers.yahoo.com/question/index;_ylt=ApfjYqHaykzhEnCDtDjBpjYh4wt.;_ylv=3?qid=20070902013243AA3gdvF
3. http://www.school-for-champions.com/science/light_refraction.htm
http://www.phy.ntnu.edu.tw/ntnujava/
4. The Usborne Illustrated Dictionary Of Physics