How do waves behave at boundaries and interfaces?

Waves at boundaries and interfaces can be reflected, refracted, or absorbed, depending on the materials involved.

When a wave encounters a boundary or an interface between two different media, several things can happen. The wave can be reflected, which means it bounces back into the medium it came from. This is similar to how light reflects off a mirror. The angle at which the wave hits the boundary (the angle of incidence) is equal to the angle at which it is reflected (the angle of reflection). This is known as the law of reflection.

Alternatively, the wave can be refracted, or bent, as it passes through the boundary. This happens because the wave changes speed when it enters a new medium, causing it to change direction. The amount of refraction depends on the angle of incidence and the refractive indices of the two media. This is why a straw appears bent when you look at it in a glass of water.

In some cases, the wave can also be absorbed by the new medium. This means that the energy of the wave is transferred to the medium, often in the form of heat. This is why you can feel warmth when you stand in sunlight.

Finally, some of the wave's energy can also be transmitted through the boundary, continuing on in the new medium. The amount of energy that is transmitted depends on the properties of the two media. For example, light can pass through a clear glass window, but not through a brick wall.

In summary, the behaviour of waves at boundaries and interfaces is a complex process that involves reflection, refraction, absorption, and transmission. The exact behaviour depends on the properties of the wave and the materials involved.