Loading…
Loading…
GCSE Physics · key term
A device that converts a varying electrical signal into sound waves.
Used by OCR
Specification P4.2j · Paper 1 (Foundation), Paper 3 (Higher)
Revise: Microphones and speakersA loudspeaker starts with a varying electrical signal and produces pressure variations in the air. It also contains a permanent magnet and a coil, but it uses the motor effect rather than electromagnetic induction.
State the energy and signal conversion clearly: a microphone converts sound pressure variations into electrical current variations; a loudspeaker or headphones perform the reverse conversion.
For a loudspeaker, identify the motor effect: an alternating current in the coil produces a force in the permanent magnet's field. Do not say that the sound induces the current.
Explain why the loudspeaker vibrates: reversing the current reverses the force, so the coil and attached cone repeatedly move in opposite directions.
Create a free account to read GCSE Physics revision notes for your exam board and track your progress.