What happens when a wave strikes a barrier? What happens when a wave strikes a barrier at an angle?
When a wave strikes a barrier, several different phenomena can occur, depending on the properties of the wave and the barrier. Let's explore the two scenarios you mentioned:
1. When a wave strikes a barrier directly (perpendicular to the surface), it undergoes a process called reflection. This means that the wave bounces off the barrier and travels back in the opposite direction. The angle at which the wave strikes the barrier is equal to the angle at which it reflects.
To understand why this happens, we can consider the wave as a series of oscillations that propagate through a medium. When the wave encounters the barrier, the oscillations reach the barrier surface and interact with it. The barrier does not allow the wave to pass through, so it reflects the wave back into the medium it came from.
2. When a wave strikes a barrier at an angle (obliquely), in addition to reflection, another phenomenon called refraction occurs. Refraction happens because the wave changes direction and speed when it enters a different medium, such as air to water or vice versa.
To understand the process of refraction, we need to consider the concept of the wavefront. A wavefront is an imaginary surface representing points in a wave that are in phase (i.e., have the same amplitude and displacement). When a wavefront encounters a barrier at an angle, the different parts of the wavefront reach the barrier at different times.
As a result, the part of the wavefront that reaches the barrier first slows down or speeds up depending on whether it is entering a denser or less dense medium. This change in speed causes the wavefront to change direction, bending towards or away from the normal (a line perpendicular to the barrier's surface). This bending is known as refraction.
In summary, when a wave strikes a barrier directly, it reflects back in the opposite direction. When a wave strikes a barrier at an angle, it reflects and undergoes refraction, changing its direction due to the change in speed as it enters a different medium.