Waves

• Longitudinal waves are oscillations which occur parallel to the direction of travel.
• In a longitudinal wave, the particles come close together and then push apart.
• When the particles are close together, this is called a compression.
• When the particles are far apart, this is called a rarefaction.
• An example of a longitudinal wave is a sound wave.
• Longitudinal waves are also called pressure waves.
• Transverse waves occur when the oscillations are perpendicular or at right angles (90°) to the direction of travel.
• Examples of transverse waves include water waves and electromagnetic waves.
• Electromagnetic waves are transverse waves.
• Electromagnetic waves range in wavelength size. The largest to smallest wavelength waves are:

  • Radio waves.
  • Microwaves.
  • Infra-red.
  • Visible Light.
  • Ultra-Violet.
  • X-Rays.
  • Gamma Ray.
• Electromagnetic waves are able to travel through a vacuum (such as space) so do not need a medium to travel through.
• Here you can see a pressure wave. The particles compress, and then push apart, leading to an area of high pressure which moves in space, and an area of low pressure which follows it.

  
• A wave is a vibration that transfers energy.
• Waves are oscillations or vibrations. All waves transfer energy.
• The matter a wave passes through does not move from its position.
• You can see information about a wave on an oscilloscope. It displays this information on a screen.
• • Wavelength - the distance between a point of a wave to the same point on the next wave.
• Peak or crest - the top of a wave.

  Trough - the bottom of a wave.
• Amplitude - the distance from the middle to the crest or trough of the wave.
• Frequency: the number of waves that travel past a single point every second. Measured in Hertz (Hz).
• This is an oscilloscope. The wavelength is the distance between two peaks. The amplitude is the distance from the middle of the wave to the peak.

  
• If we know the frequency of the wave and the wavelength, we can work out the speed it travels at. Light travels about one million times faster than sound.
• Particles move at right angles to the direction of travel in the transverse wave, and parallel to it in the longitudinal wave.