waves

• in transverse waves oscillations are perpendicular to the energy flow. e.g. surface waves on water
• in longitudinal waves the oscillations are parallel to the energy flow
• waves transfer energy
• waves pass through a resistance like water or air the resistance oscillates but does not move along the wave
• compression is high density whereas rarefaction is low density
• wavelength is the distance from any point on one wave to the equivalent point on an adjacent wave
• frequency is the number of waves passing a point each second
• amplitude is the maximum displacement of a point on a wave away from its undisturbed position
• period is the time it takes for one wave to be produced or to pass a point
• wave speed is the speed at which the energy is transferred through the resistance
• stages of measuring the speed of sound

  1. measure the distance using a trundle wheel
  2. one group clap to make a sound
  3. the other group start the stop clock when the see the clap, and stop the stop clock when they hear the clap
  4. repeat the measurements and work out the mean time
• stages of measuring wavelength in a ripple tank

  1. use a ruler to measure several wavelengths
  2. work out one wavelength

  e.g. 10 wavelengths = 23cm. 23/10 = 2.3cm
• stages of measuring frequency in a ripple tank

  1. make a mark on the card
  2. count the number of waves passing the mark and time them

  e.g. if 20 waves pass in 5.6 seconds, the frequency is 20/5.6 = 3.6Hz
• stages of measuring wave speed in a ripple tank

  1. make two marks on the card and measure the distance between them
  2. use a stop clock to measure how long a wave takes to move between the marks
• stages of investigating the speed or waves on an elastic cord

  1. put the starting mass on a mass hanger
  2. adjust the signal generator frequency and/or position of the moveable bridge until a clear wave patterns forms.
  3. measure the wavelength with a metre ruler
  4. get the frequency from the signal generator
  5. calculate wave speed
  6. change the mass on the hanger
  7. repeat and calculate the mean