This project idea comes to you from Worlds Unbound in Fredericton, New Brunswick. |
![]() |
When light hits an object, it is either reflected, refracted, or both. When light is reflected, it bounces off the surface at the same angle (the angle of reflection) that it came in (the angle of incidence). This is called the Law of Reflection.
Light can also be refracted. The light hits the surface and bends, so it leaves the surface at a different angle. This happens when light is travelling from one medium to another. For example, when light goes from air into water, it is refracted. Why? Because the light moves at different speeds through different materials. If you've ever looked down at your feet when you're in a swimming pool, you might have noticed that they look strange. The light is moving from air to water, so it refracts off your feet, making them look funny.
2nd session
To work your rainbow pin:
Why does this happen? Some of the light rays are reflected by the surface and some of the rays go through and are reflected off the bottom of the film. When the reflected rays overlap as they leave the film, some of them cancel each other out. (This is called interference.) The colour that you see is a mixture of what's left over. At another place where the nail polish is thinner, a different colour may be cancelled out. That's why you see different colours coming from different places on your pin.
You can see the same phenomenon when light reflects off a soap bubble, or off a puddle of gasoline on a wet street. This effect is called Thin Film Interference.
Physics | Chemistry | Biology | Engineering | Computer Science | Understanding Science and Technology