# Waves ~~~~~

### What you must understand!

• There two types of waves: longitudinal and transverse waves.
• Both waves only transfer energy from one point to another without physically transferring the medium the wave travels in.
• The source of a wave is a vibration or an oscillation.
• Points that are considered to be in phase must meet 3 criteria:
• They must have the same direction of motion
• They must have the same speed
• They must have the same displacement from their rest position
• Wavefront is an imaginary line on a wave that joins all adjacent points that are in phase.

### Deduction of wavelength and period from displacement-distance and displacement-time graphs

We can deduce amplitudes of the waves from both graphs. However, the graph on the left will allow us to deduce the period of the wave (displacement-time) whereas the one on the right will only provide us with the wave length (displacement-distance).

### Visualisation of Particles Movement in Longitudinal Waves In a Medium (air)

• Particles only oscillate back and forth about their individual equilibrium positions.

### Visualisation of Particles Movement in a Rope Generating Transverse Wave

• Particles only oscillate up and down about their individual equilibrium positions.

### Visualisation of Particles Movement in Water Wave

• In real life, water wave like the one below is a combination of both transverse and longitudinal motions.