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Section 3: Waves
KS3 Connections:
Exploring Science 7, 8 & 9 


a) Units
b) Properties of waves
Students will be assessed on their ability to:
3.1 use the following units: 
degree (o)                    angles
hertz (Hz)                     frequency, how many cycles per second
metre (m)                     distance
metre/second (m/s)    velocity 
second (s).                    time
3.26 understand that sound waves are longitudinal waves and how they can be reflected, refracted and diffracted
 
​Sound waves vibrate particles and can be generated from speakers or tuning forks etc. 
 They are longitudinal waves, the vibrations are parallel to the direction.
Picture
Picture
 Speed of sound is approximately:
                                          330m/s in air (depends on temperature and pressure                                       
                                          1500m/s in seawater (particles closer together compared to air)
                                           5000m/s in concrete (particles even closer together compared to liquid and gas)

​Like all other waves sound waves can be reflected (echo), diffracted and refracted.
Picture
Picture
          diffracted    (also sound through a doorway)                                            refracted     at night hot air rises(bottom diagram)
3.27 understand that the frequency range for human hearing is 20 Hz – 20 000 Hz
Picture
                       You need to know human audible range  20 - 20000HZ
3.28 describe an experiment to measure the speed of sound in air
  • Someone stands a measured distance away (100m) and fires a starter pistol or hits two symbols.
  • Use a stopwatch to start the time from when you see them fire the pistol (from the smoke) or hit the symbols
  • Stop the watch when you hear the sound.
  • You will need to repeat this, 5 - 10 times and take the average reading, this will cut down some inaccuricies.
  • Using v =d / t you can work out the speed of sound. 
  • This is inaccurate due to your reaction time (about 0.1ms).
  • You will need to do the experiment in still air.

  • You can stand 50m from a wall
  • set up a rhythm of claps so that the echo comes exactly between two claps.
  • Ask a friend to time 20 claps. 
  • During this time the wave will have travelled (50 x 2) x 20 = 2000m. (to the wall and back x 20). 
  • Now divide the distance by the time.
3.29 understand how an oscilloscope and microphone can be used to display a sound wave
Picture
Connect a microphone to an oscilloscope to produce a trace.
​Sound waves from a speaker are converted to electrical signals using a microphone. 
The oscilloscope shows these electrical signals as waves on the screen.
3.30 describe an experiment using an oscilloscope to determine the frequency of a sound wave
Picture

                                                         Time period = 5 x 3 = 15s                Time period = 5 x 0.005 = 0.025s
                                                      frequency = 1 / Time period               frequency = 1 / Time period        
                                                        frequency = 1 / 15 = 0.07hz              frequency = 1 / 0.025 = 40hz
3.31 relate the pitch of a sound to the frequency of vibration of the source
Picture
Picture

​S-cool link for hearing pitch
3.32 relate the loudness of a sound to the amplitude of the vibration
Picture
Picture
S-cool link for hearing Loudness
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  • Home
  • IGCSE Physics
    • Documents
    • Forces and Motion >
      • Syllabus revision
    • Electricity
    • Waves >
      • Syllabus revision
    • Energy Resources and Energy Transfer
    • Solids Liquids and Gases
    • Magnetism and Electromagnetism
    • Radioactivity and Particles
    • Practicals
    • Past Papers >
      • Edexcel 2011 / 2012
      • Edexcel 2015 / 2016
      • CIE 2011
  • IB Physics
  • Untitled