Refraction of Light by 2E1 Teresa Zhou

Refraction
Refraction is the change in the direction of light. Refraction is caused by the change in speed experienced by a wave when it changes medium, such as when light passes from one transparent material into another, like from air to glass, air to water, or from water to glass, and also in the opposite directions glass to air.

There is an incident ray (drawn perpendicular to the watefronts), which is a ray that shows the direction which light travels as it approaches the boundary. Similarly, refracted ray (drawn perpendicular to the wavefronts is a ray which shows the direction which light travels after it has crossed over the boundary.

During refraction, light bends first on passing from air to glass, and again on passing from glass to the air again. Light travels faster when moving from a less dense material to a denser material, such as from the air to the glass, and it bends away from the normal, but however when light moves from the glass to the air, which is from a denser material to a less dense material, it travels slower and bends towards the normal.

Refraction has some unusual effects in everyday life. Refraction can cause words to appear nearer to the surface of the glass than they actually are, so the glass block appears to be thinner than it really is. The object can also appear to be at a higher position than it actually is when under the water, like when in a swimming pool, where we think that it appears shallower than it really is. Refraction is even responsible for causing rainbows, splitting their light into the rainbow-spectrums!

Some fun facts about refraction:
Try putting a straw into a glass of water. It would appear bent.
This is because light is moving from a less dense material to a denser material, therefore it bends further away from the normal. In our eyes, we would see that it appears bent.

When a hunter wants to spear a fish that is under water, being experienced, he would aim at a little lower from where the fish is.
Light is moving from air to water, therefore light bends away from the normal. If he were to hit exactly where the fish is, he would miss and end up hitting nothing, so he has to hit lower to hit exactly where the fish is.

Try taking a photo of the waves in the ripple tank; you will see some stripes appearing on your photograph.
Ripples travel from the left and pass over a shallower region inclined at an angle to the wavefront. The waves travel more slowly in the shallower water, so the wavelength decreases and the wave bends at the boundary. The dotted line represents the normal to the boundary. The dashed line represents the original direction of the waves. The phenomenon explains why waves on a shoreline never hit the shoreline at an angle.

The angle of light refraction to create a Rainbow is 42 degrees to the eye of the observer.
The same theory, as when light moves from less dense material to a denser material. It travels faster, and it is bent away from the normal, therefore 42 degrees to the eye of the observer.