Further definitions

As an example of a wavefront, consider a rock being dropped into a pond, the peak of each ripple formed can be considered as a wavefront. This is shown in the diagram below:

There are two types of interference that can occur during superposition and they are: 

• Constructive interference - this occurs when two waves are in phase (explained below) and so their displacements are added 
• Destructive interference - this occurs when the waves are completely out of phase (explained below) and so their displacements are subtracted

The image below shows the interference of two waves (which are pictured below the resultant wave). On the left is constructive interference and on the right is destructive interference.