How does a wave's frequency affect its refraction?

A wave's frequency affects its refraction by determining the angle at which it bends when passing through different mediums.

Refraction is the bending of a wave when it passes from one medium into another. This phenomenon is governed by Snell's Law, which states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equal to the ratio of the velocities of the wave in the two different mediums. The velocity of a wave in a medium is determined by the medium's refractive index, which is in turn affected by the frequency of the wave.

When a wave with a higher frequency enters a new medium, it slows down more than a wave with a lower frequency. This is because the refractive index of a medium generally increases with the frequency of the wave. As a result, the wave bends more, and the angle of refraction is smaller. This is why different colours of light, which are simply light waves with different frequencies, refract at different angles when they pass through a prism. This phenomenon is known as dispersion.

However, it's important to note that the relationship between frequency and refractive index is not always straightforward. In some materials, the refractive index decreases with increasing frequency, a phenomenon known as anomalous dispersion. This can occur in certain circumstances, such as near the absorption lines of a material.

IB Physics Tutor Summary: In simple terms, a wave's frequency influences how much it bends, or refracts, when it moves from one medium to another due to changes in speed caused by the medium's refractive index. Higher frequency waves bend more sharply. However, this relationship can vary in some materials, leading to unusual bending patterns, known as anomalous dispersion.