Mystery #4Tier 2-3electricity / sound

How does a speaker turn a stream of electricity into music you can hear?

Down one thin wire flows a silent stream of electricity, and out of the speaker pours music: voices, drums, whole bands. Electricity makes no noise on its own, so something inside must be turning it into sound. What is going on inside that little box?

A close-up of a loudspeaker's voice coil, fine copper wire wound many times round a cylinder — Photo: Daniel Christensen · CC BY-SA 3.0 · via Wikimedia Commons

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