Friday, January 24, 2014
List of Electromagnets
An electromagnet is simply a coil of wire wound around a core. When connected to a DC voltage or power source, it attracts metal just like an ordinary magnet. However, the strength and polarity of the field can be adjusted by altering the magnitude and direction of the current. By adjusting the shape of the electromagnets core, the shape of the magnetic field may also be changed. Electromagnets are simple in concept but can appear in numerous forms.
Solenoid Electromagnets
A solenoid is an electromagnet with coil wrapped around a core of air (e.g., instead of iron). Typical voltages of solenoids are 12 and 24 volts. Solenoid actuators are used to push and pull things such as locks and valves. Almost every automobile uses a solenoid to control the starter motor, connecting it to the battery and the engine flywheel.
Electric Bell Electromagnets
You probably know the sound of the alarm bell from a fire drill at elementary school. The bell functions by means of an electromagnet. When a switch activates the current, it produces a magnetic field in which the metal arm of the bell repeatedly hits the inside or the outside of the bell. Doorbells and old alarm clocks also use similar electromagnets.
Electromagnets in Broadcast Technology
Before cable and digital technology, radio and television used electromagnets in their transmitters to send electromagnetic waves over wide geographic areas. The TV or radio antennae that received these waves could demodulate the signal (by generating its own electromagnetic wave that corresponded with the transmitted wave) and convert it into image and sound.
Superconducting Electromagnets
Superconducting electromagnets are used to produce very strong magnet fields in physics labs. The coil consists of wire cooled to hundreds of degrees below zero. In a particle accelerator, such a magnet has the power to bend the paths of particles formed from proton and ion collisions at near light speed.
Bitter Electromagnets
Bitter electromagnets are solenoids that use specially designed resistive magnetic plates in place of coil in order to resist the heat produced by an electrical current. Francis Bitter invented these plates in 1936, hence the name "Bitter" magnets. These magnets are mostly found in research laboratories.
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