A Speaker Is Secretly a Motor

A typical speaker is really a motor that only moves back and forth. At the back is a permanent magnet, and a coil sits in a narrow gap in the magnet assembly. The coil is attached to the cone. Current in the coil makes the magnet push or pull it, and the cone moves with it. Touch a 1.5V battery to a small speaker for a moment and the cone jumps to one side and stays there. Flip the polarity and it moves the other way. Feed it a current that changes strength and direction quickly, like an audio signal, and the cone vibrates and pushes air: that's sound. Steady DC just holds the cone to one side, so after one click there's no sound, while a large current from a faulty amp keeps heating the coil. That's why some amplifiers disconnect the speaker if DC shows up at the output. #Electronics #Speaker #Audio #Shorts