Transverse and longitudinal waves

The idea

Waves transfer energy without transferring matter. In transverse waves (ripples on water, electromagnetic waves) the oscillations are perpendicular to the direction of energy transfer. In longitudinal waves (sound) the oscillations are parallel to it, with compressions and rarefactions. Amplitude is the maximum displacement from rest; wavelength is the distance from one point to the same point on the next wave; frequency is the number of waves per second. Wave speed v = fλ, and period T = 1 ÷ f.

1. Identify transverse or longitudinal.
2. Use v = fλ with Hz and metres.
3. Use T = 1 ÷ f for the period.

Watch out When a wave passes, the medium oscillates; it is the energy that travels, not the water or air.