Theory -when a wave enters a medium which it moves more slowly, it's wavelength decreases. -when a wave travels from deep water to shallow water in such a way that it meets the boundary between the two depths straight on, no change in direction occurs.
-if it meets the boundary at an angle however, the direction of travel does occur. This is called refraction. -wave rays are used to describe refraction. -Normal is aline drawn at right angles to a boundary at the point where an incident wave ray strikes the boundary. -The angle formed by a reflected wave ray and the normal is called the angle of refraction. -when a wave travels at an angle into a medium in which its speed decreases, the refracted wave ray is bent towards the normal.
-if the wave travels at an angle into a medium which its speed increases, the refracted wave ray is bent away from the normal.
-the frequency of a wave does not change when its velocity changes. Therefore we might expect that the index of refraction and the amount of bending would not change for waves of different frequencies, provided the medium stayed the same. This is not always the case however. -the amount of bending and hence the index of refraction, is affected slightly by the frequency of the wave. -We can conclude that, since the index of refraction represents a ration of speeds in two media's, the speed of the waves in at least one of these media must depend on their frequency. -Such a medium, in which the speed of the waves depend on the frequency, is called a dispersive medium.
-When a refraction occurs, some of the energy is usually reflected as well as refracted.
-The amount of reflection is more noticeable when a wave travels from shallow to deep water, where the speed increases and it becomes more pronounced as the angle of incidence increases.
-An incident angle is reached where the wave is retracted at an angle approaching 90 degrees. -After that, there is no refraction and all the wave energy is reflected.
Conclusion When a wave enters a medium in which it's speed decreases, it's wavelength decreases as well. No change of wave direction occurs when a wave travels from deep water into shallow water as it meets the boundary in between the two. As a wave travels at an angle into a medium in which its speed decreases, the refracted wave ray is bent towards the normal. However , when a wave travels into a medium in which it's speed increases, the refracted wave ray is bent away from the normal. The frequency of a wave does not change when it's velocity changes. The frequency of the wave slightly affects the amount of bending of refraction.