Microphones and Loudspeakers [H]

Microphones and loudspeakers are everyday devices that use the principles of electromagnetism. Loudspeakers use the motor effect to convert electrical signals into sound, while microphones use the generator effect to convert sound into electrical signals. This is Higher tier content from AQA GCSE Physics specification 4.7.2 and 4.7.3.

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How a Loudspeaker Works

A loudspeaker converts an electrical signal (alternating current) into sound waves.

Components of a Loudspeaker

Component	Role
Permanent magnet	Provides a strong, constant magnetic field
Coil of wire (voice coil)	Carries the alternating current signal; attached to the cone
Paper or plastic cone	Vibrates to produce sound waves
Suspension (spider and surround)	Allows the cone to move back and forth freely

graph LR
    subgraph "Loudspeaker Cross-Section"
        AC["AC Signal Input"] --> VC["Voice Coil (wrapped around former)"]
        PM["Permanent Magnet (cylindrical)"] -.->|"Provides magnetic field"| VC
        VC -->|"Motor effect: force on coil"| CONE["Paper Cone"]
        CONE -->|"Vibrates"| SOUND["Sound Waves"]
    end

Step-by-Step Operation