How is an electromagnet used in a speaker?

Question

How is an electromagnet used in a speaker?

Answer 1

The audio signal is sent to a coil of wire that is in the field of the permanent magnet. The varying voltage causes a varying magnetic field, which with the permanent magnet, causes the coil to move back and forth. The coil is attached to the speaker diaphragm and causes it to move back and forth, generating sound.

Answer 2

http://www.howstuffworks.com

Answer 3

An electromagnet is used to push and pull on a cone. The cone is attached to a diaphragm that moves air to recreate the sounds.

Answer 4

To recreate the vibrations of the sound waves.

A electrical signal is sent to speaker via wires and it creates a magnetic field of varying strengths, that turns on and off.  This causes vibrations and the metal coil on the back paper cone, in front of the electromagnetic, picks up the vibrations and amplifies them.  The coil is made out of ferris metal so the changing magnetic field moves it, thus moving the paper in front of the speaker.

According to Wikipedia:  http://en.wikipedia.org/wiki/Loudspeaker

"A loudspeaker, speaker, or speaker system is an electromechanical transducer that converts an electrical signal to sound. The term loudspeaker can refer to individual transducer devices (otherwise known as drivers), or to complete systems consisting of an enclosure incorporating one or more drivers and electrical filter components. Loudspeakers, just as with other electro-acoustic transducers, are the most variable elements in an audio system and are responsible for the greatest degree of audible differences between sound systems.

To adequately reproduce a wide range of frequencies, most loudspeaker systems require more than one driver, particularly for high sound pressure level or high accuracy applications. Individual drivers are used to cover different frequency ranges. The drivers are named subwoofers (very low frequencies), woofers (low frequencies), mid-range speakers (middle frequencies), tweeters (high frequencies) and sometimes supertweeters which are drivers optimized for higher frequencies than a normal tweeter....

The most common type of driver uses a lightweight diaphragm connected to a rigid basket, or frame, via flexible suspension that constrains a coil of fine wire to move axially through a cylindrical magnetic gap. When an electrical signal is applied to the voice coil, a magnetic field is created by the electric current in the coil which thus becomes an electromagnet. The coil and the driver's magnetic system interact, generating a mechanical force which causes the coil, and so the attached cone, to move back and forth and so reproduce sound under the control of the applied electrical signal coming from the amplifier. The following is a description of the individual components of this type of loudspeaker.

The diaphragm is usually manufactured with a cone or dome shaped profile. A variety of different materials may be used, but the most common are paper, plastic and metal. The ideal material would be stiff (to prevent uncontrolled cone motions), light (to minimize starting force requirements) and well damped (to reduce vibrations continuing after the signal has stopped). In practice, all three of these criteria cannot be met simultaneously using existing materials, and thus driver design involves tradeoffs. For example, paper is light and typically well damped, but not stiff; metal can be made stiff and light, but it is not usually well damped; plastic can be light, but typically the stiffer it is made, the less well-damped it is. As a result, many cones are made of some sort of composite material. This can be a matrix of fibers including Kevlar or fiberglass, a layered or bonded sandwich construction, or simply a coating applied to stiffen or damp a cone."

Answer 5

speakers mainly have permanent magnets.

The electromagnetic element is the coil of wire that operates in the permanent magnet's field. The alternating current produced by the amplifier and driven into this coil of wire is responsible for interacting with the permanent magnetic field and generates a force against it.

As the speaker's coil is usually attached to a cone (the visible portion of the speaker) the vibrations of the electromagnetic coil interacting with the permanent magnet are translated through the speaker cone into pressure waves in the air which we can hear as sound.