In a speaker, an electromagnet is positioned in a constant magnetic field created by a permanent magnet. These two magnets –– the electromagnet and the permanent magnet –– interact with each other as any two magnets do. The positive end of the electromagnet is attracted to the negative pole of the permanent magnetic field, and the negative pole of the electromagnet is repelled by the permanent magnet’s negative pole.
When the electromagnet’s polar orientation switches, so does the direction of repulsion and attraction. In this way, the alternating current constantly reverses the magnetic forces between the voice coil and the permanent magnet. This pushes the coil back and forth rapidly, like a piston. When the coil moves back and forth, it pushes and pulls on the speaker cone. This causes the air in front of the speaker to vibrate creating sound waves. The electrical audio signal can also be interpreted as a wave. The frequency and amplitude of this wave, which represents the original sound wave, dictate the rate of movement of the voice coil and the distance that the voice coil moves [magnitude of the movement]. These, in turn, determine the frequency and amplitude of the sound waves produced by the diaphragm.
0 Comments