Describe how waves interact at boundaries.

Waves interact at boundaries through reflection, transmission, and absorption, depending on the properties of the boundary material.

When a wave encounters a boundary, it can be reflected, transmitted, or absorbed. Reflection occurs when a wave bounces back into the medium it came from. This is common when light hits a mirror or sound waves bounce off a wall. The angle at which the wave hits the boundary (the incident angle) is equal to the angle at which it is reflected (the reflected angle). This principle is known as the law of reflection.

Transmission, on the other hand, involves the wave passing through the boundary and into a new medium. This is often accompanied by refraction, a change in the direction of the wave due to a change in its speed. The amount of refraction depends on the difference in wave speed between the two media, as described by Snell's law. For example, when light passes from air into water, it slows down and bends towards the normal (the line perpendicular to the boundary).

Absorption is the third way waves can interact with boundaries. This is when the wave's energy is absorbed by the boundary material, often converting it into heat. The amount of absorption depends on the properties of the boundary material. For instance, dark, rough surfaces tend to absorb more light than light, smooth ones.

In reality, most boundaries cause a combination of reflection, transmission, and absorption. The proportions of each depend on the properties of the wave (such as its frequency and angle of incidence) and the boundary material (such as its density and surface texture). For example, when light hits a piece of glass, some of it is reflected, some is transmitted and refracted, and a small amount is absorbed.

In conclusion, the interaction of waves at boundaries is a complex process that involves reflection, transmission, and absorption. Understanding these interactions is crucial for many areas of physics, from optics to acoustics to electromagnetic theory.