Waves Revision (P6)

Waves Revision (P6)

1. Transverse waves

   • Oscillations are perpendicular (90 degrees) to the direction of the energy transfer.
   • All electromagnetic waves
   • Ripples and waves in water
   • A wave on a string

2. Longitudinal waves

   • Sound waves
   • Oscillations are parallel to the direction of the energy transfer
   • Ultrasound
   • Tsumnami
   • The speed of sound in air is around 330m/s

3. Waves

   • Amplitude
     • Maximum displacement of a point on a wave from its undisturbed position
   • Wavelength
     • The distance between the same point on two adjacent waves ( between the trough of one wave and the trough of the next wave)
   • Frequency
     • The number of complete waves passing a certain point per second.
     • Measured in Hertz
     • From the frequency , you can find the period of a wave using:
       • (period) T=1/f (frequency)
   • Waves can be longitudinal or transverse
   • Wave speed = Frequency x wavelength

4. PRACTICALS

   • Use an oscilloscope to measure the speed of sound
     • By attaching a signal generator to a speaker you can generate sounds with a specific frequency
     • You can use two microphones and an oscilloscope to find the wavelength of the waves generated.
   • Measure the speed of water ripples using a ripple tank
     • Using a signal generator attached to the dipper of a ripple tank you can create water waves at a set frequency
     • This is a set up suitable for investigating waves
       • It allows you to measure the wavelength without disturbing the waves
   • Waves on Strings
     • When you turn on the signal generator and the vibration transducer the string will start to vibrate.
     • Adjust the frequency until there is a clear wave on the sring
       • The frequency is whatever you set the signal generator to
     • This is a good practicla to measure the wavelength as it clearly shows the waves and it is easy to count them
       • Count as many waves as you can then divide to get the mean half wavelength. Double to get full wavelength

5. Waves can be Absorbed, transmitted or reflected