Sound & Oscilloscopes (Edexcel IGCSE Physics (Modular)): Revision Note

Sound & oscilloscopes

• 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