A wave can be thought of as a disturbance that travels through a medium from one location to another location. Waves are produced as energy is transmitted through a medium such as air or water. Electricity produces microscopic waves that travel through a conductor such as a copper wire.

  • Waves propagate through a medium as atoms and molecules bump into each other producing a domino affect.
  • Waves share common features such as amplitude, crests, direction of travel, frequency and wavelength.
About waves in water
  • If you throw a stone into a pond it produces a series of ripples (waves) that spread out in concentric circles before crashing against obstacles.
  • Seen from a boat at sea, waves form as the wind and tide apply forces that disturb the water.
  • In general terms:
    • The frequency of waves in water can be counted as individual waves rise to a crest at any given point.
    • Wavelength can be calculated by looking at the distance from the crest of one wave to the crest of the next.
    • Amplitude can be measured by looking at the distance from the top of a crest of a wave to the bottom of the next trough.
    • When looking at waves on water it is easy to see in what direction they are travelling.
    • The energy carried by waves at the beach is obvious when you go for a swim and are thrown head-over-heels.
Electromagnetic waves
  • Electromagnetic waves are invisible either because they are too small to see or because our eyes don’t respond to them:
    • The wavelength of some radio waves can be measured in metres but our eyes are not tuned to see them.
    • When we see colours around us electromagnetic waves are entering our eyes but their amplitude, frequency and wavelength are too small to see.
    • Whilst we may not be able to see electromagnetic waves we may be able to sense them as heat or feel a buzz in a wire.
  • Electromagnetic waves can vary in size so much that their wavelength may need to be measured in kilometres or trillions of picometres (1012) .
  • The frequency of electromagnetic waves may be as infrequent as 1 per second (1 hz per second) or as frequent as a quadrillion per second (1015).