THE diffraction can be defined as the ability of waves in getting around obstacles. When a wave collides with an obstacle that has an opening with dimensions comparable to its own length, the parts of the wave passing through the open space widen and reach the regions opposite the obstacle.
In the image above, after the waves pass through the crack, they become circular, so they can reach the entire region behind the obstacle.
slit size
As the size of the slit through which the waves pass increases, in relation to the wave-length, the diffraction phenomenon becomes less intense. In the image below, the obstacle has a larger opening than in the previous image. This does not prevent the occurrence of diffraction, but it happens less intensely.
Diffraction and wave types
The diffraction phenomenon occurs with all types of waves. With sound waves, for example, the occurrence of this phenomenon can be seen when two people maintain a conversation even when there is an obstacle interposed between them, such as a wall.
By Joab Silas
Graduated in Physics
Source: Brazil School - https://brasilescola.uol.com.br/o-que-e/fisica/o-que-e-difracao.htm