What is the function of a permanent-magnet loudspeaker?

A permanent-magnet loudspeaker operates by utilizing the interaction between a coil of wire and a magnetic field created by a permanent magnet. When an audio signal—represented by an electrical current—flows through the coil, it generates a magnetic field that interacts with the magnetic field of the permanent magnet. This interaction causes the coil, and consequently the attached cone, to move back and forth. The movement of the cone creates sound waves, allowing the speaker to reproduce the audio signal.

This mechanism is essential for the function of loudspeakers, as it directly translates electrical energy into mechanical energy to produce sound. Other options, such as amplifying sound without electrical input or creating sound by friction, do not accurately describe the fundamental operation of a permanent-magnet loudspeaker, as they do not involve the precise physical interactions that make sound generation possible in this context. The creation of static sound is also not applicable, since a loudspeaker’s purpose is to reproduce dynamic sound changes rather than static noise.