It is the phenomenon that occurs when a wave hits an obstacle and returns to the propagation medium, maintaining the characteristics of the incident wave.
Regardless of the wave type, its velocity module remains unchanged after reflection as it continues to propagate in the same medium.
One-dimensional wave reflection
This analysis shall be divided into fixed-end and free-end oscillations:
With fixed end:
When a pulse (half-wave) is generated, it causes each point of the rope to rise and then return to its original position. However, upon reaching a fixed end, such as a wall, the force applied to it by the principle of action and reaction reacts. over the rope causing a movement in the direction of pulse application, in a reverse direction, generating a reflected pulse. As shown in the figure below:
For this case it is often said that there is phase inversion since the reflected pulse performs the opposite movement of the incident pulse.
With free end:
Considering a rope attached by a ring to an idealized rod, therefore without friction.
Upon reaching the ring, movement is continued, although there is no displacement in the direction of the pulse, only in the direction perpendicular to it. Then the pulse is reflected towards the application, but in reverse. As shown in the picture:
For these cases there is no phase inversion, as the reflected pulse performs the same movement as the incident pulse, only with the opposite direction.
The free end can be obtained by tying the rope to a very light, flexible and inextensible string.