The Difference Between Reflection and Refraction

, , Leave a comment

Reflection is the return off light, heat or sound after it strikes the boundary between two different mediums.

The receiving body or surface, does not absorb the projected light heat or sound waves, but throws them back.

When light strike a mirror the rays bounce off in a predictable manner, following the Law of Reflection. The image of the source of the light is reflected in the mirror. This happens with any surface that does not absorb light.

If the reflecting surface is smooth the image viewed is clear, but if the surface is irregular the reflection is diffused, and the image is blurry.

Sound waves also reflect off surfaces that do not absorb them. An echo is caused by the reflection of sound. In an auditorium, the stage is often backed by a curved surface (a parabola). When sound waves reflect of a parabola they travel in a straight line, and can be directed at the audience.

Heat waves also reflect of surfaces that do not absorb heat. White is a popular colour in hot places as the heat waves bounce off white surfaces. The heat from the hits the surface of the earth and is reflected back heating the atmosphere on its journey back.

Thus heat, light and sound are all reflected, or thrown back by surfaces that do not absorb them.

Refraction sounds the same as reflection but is in fact quite different. It is the change in the direction of wave as it passes from one medium to another and changes its speed.

Light is refracted when it passes from one transparent medium to another. The mediums allow light to pass through them. The speed of light differs as it passes through different transparent mediums. As light passes from a vacuum or air to glass or water, it slows down. Therefore, if you put a pencil in a glass of water it seems to be bent. As the light waves pass from the air to the water, they slow down and bend causing the pencil to appear misshapen.

Sound too is refracted as it speed varies through different mediums. It is usually easier to hear far away sounds at night. This phenomenon is attributed to the diminishing of the surrounding sounds as the night progresses. However the phenomenon is present even it very silent places.

During the day, campers on one side of lake can see the campers on the other side but they cannot hear them. At night the situation reverses, they can be heard but not seen. This is caused by the refraction of sound. In the day, the air closer to the ground is hotter and the sound waves travel faster. Higher up the air is cooler and the waves are slower. This creates a sound shadow zone making the groups on either side aurally invisible to one another. At night, due to the temperature lapse, the waves closer to the ground are travelling slower than those higher up and the sound travels clearly to the other side.

Heat reflecting off the ground on a very hot day, makes the air near the ground much hotter than the air above causing light rays to refract. As the light is moving through the same medium (air) this is known of heat refraction. It causes people in deserts to see mirages.

Basically reflection is the bouncing back of heat, light or sound waves that caused the image or sound to be duplicated. Refraction is the change in direction of waves as they pass through mediums that change their speed. Refraction distorts the sound or image.


Leave a Reply