What is 3 examples of light 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 so-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.

Answer 2

Introduction:

Here are some common examples of Refraction, including some ideas of previous answers.

These are only examples and not explanations. The reader is encouraged to seek more detail if something is not clear or leave a comment if something seems to be wrong.

Refraction:

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. Refraction is not reflection and it is not diffraction.

Examples:

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 a great example of refraction. It also illustrates that the degree 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 mist or small drops of water. There is also reflection and diffraction 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 exits 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 upward.

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 so-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 created in one depth that encounter the edge at an angle will be seen to change direction. This is most obvious for very shallow depths of 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 change of speed 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. Air near a hot surface does this. See the example about a mirage.) 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.

10. Finally, a very interesting example of refraction is a mirage. This is typically seen when air has been heated above a hot surface such as a highway under summer sunlight. There are, of course, the stories about mirages in deserts and they are true mirages but they are not images of an oasis. In a mirage, light from some low part of the sky or from an object on the horizon enters the area of hot air that is just above the heated surface. That air, being warm, has lower density. Lower density air has a smaller index of refraction, so this is an example of light from a high density region entering a low density region. In doing so, light changes its angle away from the vertical, i.e. bends towards the horizontal, as a result of the gradient in the index of refraction. In fact the light rays that are most horizontal to begin with will bend back up and emerge from the low density air moving upward at a small angle. The result is that the observer sees this light coming up from the hot air layer that is distant (at a low angle) from the observer. That light is the color of the background, i.e. the sky or the horizon, and thus one "sees" the sky or horizon by looking slightly downward. On can understand, how in a desert, an observer seeing a dark region far off would interpret this as an oasis but you don't have to be in a desert. Kneel down and look along a hot highway when there is very little air movement to disturb the layer of heated and less dense air.

11. If one is willing to construct an experiment and one has a small laser such as one uses as a laser pointer or in a laser level, there is an experiment that does the opposite of the mirage example. All you need is s fish tank (no fish), water, sugar, mirror and laser. The goal is to do the opposite of the mirage and create a layer that has a higher density at the bottom so light bends downward in a vertical density gradient and then bounces back up from the mirror. Fill the fish tank mostly full of water (4 or 8 inches or 10-20 cm) and place the mirror on the bottom, reflecting side up. Then add sugar equal to 10% of the mass of water, but DO NOT STIR. Pour the sugar in so it is more or less uniformly distributed over the bottom of the tank. Leave the tank very very still and quite for 24 hours and the sugar at the bottom will dissolve but most of the sugar stays in the lower few centimeters and makes the index of refraction a few percent larger in the bottom. Now, point the laser so the light travels horizontally. The vertical gradient produced by the sugar concentration will cause the beam to bend. If the tank is long enough and a mirror is placed on the bottom, the beam will "bounce" off the bottom of the tank.