What is the function of a of magnet in a speaker?

Question

What is the function of a of magnet in a speaker?

Answer 1

The speaker magnet is there to provide a permanent magnetic field for the the speaker coil, which is embedded in the paper of the speaker cone.  When the audio signal flows throw the speaker coil it generates a small magnetic field the strength of which varies with the strength of the audio signal.  This small magnetic field is repelled by or attracted to the permanent magnetic field produced by the speaker magnet.  Thus the paper cone moves away from or closer towards

the back of the speaker.  Hence as the strength of the audio signal wiggles the paper cone wiggles back and forth, and you get sound waves that match the audio signal.

Only the field in front of the speaker magnet (where the speaker cone is located) is of any use.  The field that comes out the back of the magnet serves no purpose, and you might as well use it to stick the speaker to the fridge.

Answer 2

If you were to examine the waveform applied to a speaker coil, you would notice it has a positive component and a negative component (i.e. it is a sine wave). If we were to use soft iron pole pieces (instead of a permanent magnet) these voltage excursions would induce a magnet into the iron pole piece of opposite sense each half of the waveform. The coil would be attracted to this magnet each half wave (i.e. twice in the same direction each full wave). This is not what we want. This effectively doubles the frequency of the sound wave from the diaphragm.

To get around this, we make the pole pieces magnetic Now, the applied waveform will attract the magnet and on the next half will repel it. This will result in complete reproduction of the original waveform.

Answer 3

When an electrical signal is applied to a wire coil inside the speaker, it generates a magnetic field whose strength depends on the strength of the signal. The speaker cone, with its attached magnet, is repelled and attracted to this electromagnet, moving it back and forth, and creating the sound waves you hear.