Welcome to practical physicsPracticle physics - practical activities designed for use in the classroom with 11 to 19 year olds

Mechanical waves and superposition

This sequence of experiments allows students to see what happens when any number of pulses or waves pass through each other. Amazingly, each pulse or wave continues on its way as if there had been no encounter. Yet, at every place where the pulses or waves cross, they produce a combined effect generally called wave interference.

‘Interference’ is an unfortunate term, given that the waves pass through each other unchanged. There is a better way of thinking about what happens: at each point where waves cross, the resultant displacement can be found by adding together the separate displacements contributed by each of the waves – a process called wave superposition.


Watching one ripple crossing another

Interference with two sources, using fingers

Interference with two sources, using vibrators

Interference with plastic wave model

Path differences and phase difference

Transverse waves on a spring

Waves on water

Waves with trolleys 

Related Guidance

Using ripple tanks

Asking questions

Classroom management in semi-darkness

Using wave simulations 

Waves: basic terms & graphical representation

The speed of water waves

The speed of a wave in a tethered trolley system

Superposition effects as a characteristic of wave motion