Sound & Oscilloscopes (Edexcel IGCSE Physics)

• An oscilloscope is a device that can be used to study a rapidly changing signal, such as:
  • A sound wave
  • An alternating current

An oscilloscope is used to display sound as a waveform

Oscilloscopes have lots of dials and buttons, but their main purpose is to display and measure changing signals like sound waves and alternating current

• When a microphone is connected to an oscilloscope, the (longitudinal) sound wave is displayed as though it were a transverse wave on the screen
  • The properties of longitudinal and transverse waves are explained in the revision note Transverse & longitudinal waves
• The time base (like the 'x-axis') is used to measure the time period of the wave

An explanation of the sound waveform as displayed on an oscilloscope

A sound wave is displayed as though it were a transverse wave on the screen of the oscilloscope. The time base can be used to measure a full time period of the wave cycle

• The height of the wave (measured from the centre of the screen) is related to the amplitude of the sound
• The number of entire waves that appear on the screen is related to the frequency of the wave
  • If the frequency of the sound wave increases, more waves are displayed on screen