Waves & Wave Properties

• Waves: vibrations that transfer energy through different mediums away from the source
• Waves can travel through a medium (e.g. air or water) or a vacuum (no particles).
• Waves transfer energy without transferring matter.
• Medium: a thing that a wave travels through
• Waves move through a medium from one place to another.

  Waves do not create the medium.

  (e.g. strings, water, waves, air)
• Waves can be classified based on the medium they travel through.

  • Mechanical waves require a physical medium (with particles) to travel in.
  • Electromagnetic waves travel in empty space.
• Types of Waves

  • Transverse waves: wave travel in perpendicular to the direction the wave is travelling in. (e.g. electromagnetic waves, seismic waves)
  • Longitudinal waves: energy transfer is in the same direction as the wave motion. They cannot move in a vacuum. (e.g. sound waves)
• Properties of Waves:

  • wavelength
  • amplitude
  • period
  • frequency
  • wave speed

  
• Crest: highest point on a wave above its undisturbed position.
• Trough: lowest point on a wave above its undisturbed position.
• Wavelength: distance between one point on the wave to the same point on the next.

  • Measured in metres
  • Given symbol - $\lambda$
• Amplitude: the maximum distance of a wave from its undisturbed position.

  • Unit - M (metres)
• ($f$) Frequency: the number of waves passing a point in a second.

  • Measured in Hertz (Hz)
• (T) Period: the time to complete one complete cycle.

  • Unit - seconds (s)
• Wavelength:

  • the length of one wave cycle
  • the distance from crest to crest or trough to trough
  • increases as the distance between two consecutive points increase
  • associated with the energy of an electromagnetic wave
• Frequency:

  • the number of times a wave cycles in one second
  • increases as the number of oscillations per second increases
  • the number of oscillations or vibrations in one second
  • associated with the energy of an electromagnetic wave
• Amplitude:

  • the height of a wave
  • the maximum displacement of a wave from its rest position
  • the distance from equilibrium to a crest or trough
  • associated with the energy of a mechanical wave
• The Wave Equation:

  • wave speed: the distance travelled by a wave each second
  • the wave equation describes the relationship between frequency & wavelength
• Wave Equation:

  • V = $f$ x $\lambda$
  • V = wave speed, measured in m/s
  • $f$ = wave frequency, measured in Hz
  • $\lambda$ = wavelength, measured in m