What are some common examples of refraction?

Answer 1

Refraction is the bending (changing direction) of light (or other wave) as it passes from one medium to another. Waves also change speed when refraction occurs.

Most of the examples of refraction that people encounter in daily life involve light and either glass or water, but all waves exhibit refraction, including sound and water.

1. A relatively pure example of refraction can be observed if one places a straight object like a pencil partly in a glass of water and then observes the apparent change in the direction of the image of the straight object when it crosses the surface of the water.

2. A prism is an example of refraction. It also illustrates that the extent of refraction of light depends on the color. In a prism, light is refracted as it enters and as it leaves the prism and the light waves of different colors change directions by different amounts so that when they exit the colors are seen at different angles.

3. Rainbows have color because of refraction in a manner similar to a prism. The rainbow results when light waves encounter drops of water. There is also reflection involved and a full explanation is more complicated than the case of a prism.

4. All lenses (including the lenses in eye glasses) function because of refraction. Light enters the lens on one side and because the surface of the lens is curved, the angle of light inside is different depending on the place on the lens surface where it entered. That is called focusing light. It happens again as the light exist the lens. The eye itself has a lens that operates because of refraction and creates the image on the retina of the eye.

5. When you look into water, the objects that you see are not in the location where the image appears. Native peoples who hunted fish with a spear learned that you do not through the spear at the image of the fish because the angle of the light changes coming out of the surface of the water and makes it appear as though the fish is slightly displaced.

6. Sound refracts as does any other wave. One can not easily notice this, but if you are under water and sound enters from the air, the apparent direction will shift by some angle.

7. Water waves refract and it is easily demonstrated with a co-called ripple tank. When the depth of water changes, so does the speed of a wave. In a ripple tank one can place a flat surface on the flat bottom of a tank so there are two different water depths separated by a straight edge. Waves creates in one depth that encounter the edge at an angle will be seen to change direction. This is most obvious for very shallow depths around a centimeter.

8. Ocean waves change speed and so also demonstrate refraction but it is not clearly seen unless there is an edge such as described for the ripple tank. Ocean waves are a different sort of wave than a ripple but still can show diffraction. One can obviously see the change in speed and wavelength of waves as they come to a shore and that is related to the refraction process.

9. In old glass windows the glass is sometimes not very flat and ripples in the glass are evident. (Ripples in water give the same effect.) When you view an image through rippled glass the image is distorted because that light that entered was bent when it came in at an angle different than it was bent on the way out. The bending is refraction and the same kind of refraction as with a lens, but the ripples are irregular where as a lens is carefully smoothed.