Explain how a loudspeaker converts variations in current into sound waves.

Edexcel GCSE Physics (1PH0) — 13.1 Electromagnetic induction (Phys only) · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

A loudspeaker is connected to an audio amplifier. When a signal is played, the loudspeaker produces sound that matches the original audio signal.

Model answer (4 marks)

Varying current flows into the coil of the loudspeaker.
The current creates a magnetic field that interacts with the magnetic field of the permanent magnet.
This interaction exerts a force on the coil, causing it to move or vibrate.
The vibrating coil moves the attached cone/diaphragm, producing pressure variations in the air that are heard as sound waves.

Examiner tips

  • Use the exact sequence of events: current → magnetic field → force → coil movement → cone vibration → sound.
  • Show the cause–effect link clearly; each step earns a mark.

Common mistakes

  • Confusing the coil’s magnetic field with the permanent magnet’s field.
  • Omitting the role of the cone/diaphragm in producing sound.

Mark scheme (4 marks)

  1. Varying current flows into the coil of the loudspeaker
  2. The magnetic field from the coil interacts with the magnetic field of the permanent magnet
  3. This causes the coil to move / vibrate
  4. The vibrating coil causes the cone/diaphragm to vibrate, producing pressure variations in the air that are heard as sound waves

Key terms in this question

loudspeaker

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