transverse and longitudinal waves

• Sound is an example of a longitudinal wave, while light is an example of a transverse wave.
• Waves transfer energy from one place to another without transferring any matter (stuff)
• Waves transfer energy in the direction they are travelling
• Transverse waves


  Oscillations (vibrations) are perpendicular (at 90) to the direction of energy transfer
• Transverse waves


  • All electromagnetic waves, e.g. light
  • Ripples and waves in water
  • A wave on a string
• Longitudinal waves


  Oscillations are parallel to the direction of energy transfer
• Longitudinal waves


  • Sounds in air, ultrasound
  • Shock waves, e.g. some seismic waves
• Wave speed


  The speed at which energy is being transferred (or the speed the wave is moving)
• Wavelength


  The distance between the same point on two adjacent waves (e.g. between the trough of one wave and the trough of the wave next to it)
• Frequency


  The number of complete waves passing a certain point per second, measured in hertz (Hz)
• Period


  The amount of time it takes for a full cycle of the wave
• A radio wave has a frequency of 120*10^-6 Hz
• Finding the wavelength of the radio wave

  Given:

  Frequency = 120*10^-6 Hz

  Speed of radio waves in air = 30*10^8 m/s

  Wavelength = speed / frequency

  = (30*10^8 m/s) / (120*10^-6 Hz)

  = 2.5 m
• A wave has a wavelength of 7.5 cm