Waves and Their Properties
Ever noticed how a leaf floating on a pond just bobs up and down when waves pass by, rather than getting swept away? That's because waves transfer energy, not matter - one of the most important things to remember about wave behaviour.
Waves are vibrations that carry energy from one place to another without moving the actual material. Think of a Mexican wave in a football stadium - the wave moves around the stadium, but each person stays in their seat. The amplitude is the maximum height of a wave from its resting position, whilst the wavelength is the distance between two identical points on neighbouring waves.
You'll need to know about frequency too - this measures how many complete waves pass a point each second, measured in hertz (Hz). The period is simply how long one complete wave takes to pass by. These concepts link together in wave equations you'll use in calculations.
Transverse waves oscillate perpendicular to their direction of travel (like waves on water), whilst longitudinal waves vibrate parallel to their direction (like sound waves). Longitudinal waves have compressions (squeezed areas) and rarefactions (stretched areas) instead of peaks and troughs.
Quick Check: Sound waves making a candle flicker and a slinky spring bouncing are perfect examples of energy transfer without matter movement - the candle stays put, and the slinky doesn't travel down the room!