At its core, a loudspeaker is a transducer, a device that converts one type of energy into another. For loudspeakers, it takes electrical energy and converts it into mechanical wave energy, or sound waves. The most common type of loudspeaker is known as a moving coil speaker, named after the physically moving copper coil at its centre. The voice coil, as it’s known, acts as an electromagnet, which interacts with the magnetic force of a permanent magnet which surrounds it. When an electrical current is passed through the coil, it creates a magnetic field that flows in an opposing direction to the static magnetic field of a permanent magnet. This magnetic interaction either moves the coil forward or backwards depending on the electrical current the speaker is exposed to – the bigger the current, the stronger the attraction and repulsion between the two magnets.
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