Simple Explanation

The voltage a speaker generates after the signal stops, as its cone keeps moving.

Concise Technical Definition

A reverse voltage produced by the speaker’s voice coil moving through a magnetic field after the audio signal stops, acting like a generator.

Layman-Friendly Analogy

Imagine pushing a swing and then stopping; it keeps moving and pushes back against you. That’s back-EMF in a speaker.

Industry Usage Summary

In audio, back-EMF is relevant in speaker design and amplifier damping. It's the reverse energy created by the speaker that can affect sound clarity and amplifier performance if not properly controlled.

Engineering Shortcut

Voltage pushed back into the amp by a moving speaker cone.

Full Technical Explanation

Back-EMF refers to the phenomenon where, after an audio signal stops, a speaker's cone continues to move due to inertia. This movement causes the voice coil to cut through the speaker’s magnetic field, generating a voltage in the reverse direction (like a microphone). This voltage attempts to send current back into the amplifier. Managing back-EMF is important for accurate playback and is why damping factor and amplifier control are critical. Ideally, a speaker should “see” zero ohms (a dead short) to stop motion cleanly.