Two waves with phase difference 180° have resultant of amplitude

The superposition principle of waves states that when two or more waves pass through a point at the same time, the disturbance at that point is the sum of the disturbances each wave would produce individually. This principle applies to many different types of waves, including water waves, sound waves, and electromagnetic waves.  The superposition principle is an important idea that can explain phenomena such as interference, diffraction, and standing waves.  For example, if two waves travel simultaneously along the same stretched string in opposite directions, the net displacement of any... Show more

The superposition principle of waves states that when two or more waves pass through a point at the same time, the disturbance at that point is the sum of the disturbances each wave would produce individually.

This principle applies to many different types of waves, including water waves, sound waves, and electromagnetic waves. 

The superposition principle is an important idea that can explain phenomena such as interference, diffraction, and standing waves. 
For example, if two waves travel simultaneously along the same stretched string in opposite directions, the net displacement of any element of the string at a given time is the algebraic sum of the displacements due to each wave. The resultant wave is a sinusoidal wave, traveling in the positive X direction. 
 

Related Test: A Level Physics Practice Test: Waves 

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