Solenoids
Solenoids are electromagnets that are specially designed, and consists of the coil in an armature. An armature is a movable iron core. Solenoids are also three-dimensional coils that are wrapped around a metallic core. When an electric current passes through the metallic core, it produces an electrical current. The important aspects about solenoids are that they control magnetic fields and are used as electromagnets.
Function
Solenoids work because a magnetic field is wrapped around a wire, and the current flows through that wire. When a coil is made of many turns of wire, the magnetic field becomes increasingly stronger, and it begins to flow around the coil, going through the center. The coil of the solenoid begins to become energized with a powerful current; this causes the core to increase the flux linkage. Flux linkage is the coil in conducting wire, which a magnetic field passes through. The numbers of turns determines the amount of flux in the coil. Solenoids continue to work because the core increases the flux linkage, by closing the air gaps between cores. Generally, the movable core is spring-loaded, so when the current is turned off, it allows the core to retract. The relationship between the forces generated is proportional to the square of the current, and the forces generated are inversely proportional to the square length of their air gap. Solenoids have also been used to start or stop the mechanical contact between two different electrical leads. They are able to function, because their applications include electromechanical control elements and power switches. The coil in solenoids is attached to the diaphragm of an audio speaker or other applications.
Uses
Solenoids are used for turning applications on and off, such as: triggering, locking and latching. They are found in copy machines, washing machines, car doors, audio speakers, bumpers and plungers.
Tags: magnetic field, flux linkage, forces generated, metallic core, passes through, proportional square