When a magnet runs on electricity, it is considered an electromagnet. These devices only create a magnetic field when they are turned on, and they can be set at different levels of power. Switching the direction the electricity flows through a magnet can reverse its poles, which has useful applications. Electromagnets form an integral part of a number of different machines.
Particle accelerators are machines that physicists use to study the nature of matter and energy. They are very large machines that accelerate ions through an electrical field so that they eventually collide with another particle. These collisions help scientists get a close look at subatomic particles and their interactions. Electromagnets are used to create a constant magnetic field that accelerates particles into motion and keeps them in motion for as long as they're needed to be. Electromagnets were first used in particle accelerators in the early 1930s with the cyclotron, which garnered American physicist Ernest O. Lawrence a Nobel Prize. The betatron is another particle accelerator that employs electromagnets. An alternating current is applied to these magnets in order to maintain a constant radius of the particles (typically, electrons).
Stepper Motor Machines
Stepper motors can be found in many different machines, including laser printers, copying machines, image scanners, CD-ROMs, and certain factory machines. Stepper motors work by employing a series of stationary electromagnets situated at the base of a rotating shaft or rotor. The electromagnets are turned on and off, one after another, to direct the rotor in a circular motion. There are a number of different types of stepper motors, from those that use only two electromagnets to those that use three, four, or even more. They are popularly used in so many different machines, such as those listed above, because of their low cost, simplicity of construction, and ruggedness.
One of the most important machines, arguably, that electromagnets are part of are magnetic resonance imaging (MRI) machines, used in the health care field. Using nuclear magnetic resonance (NMR), MRIs create a series of cross-sectional images of the human body. MRIs use electromagnets to apply finely crafted radio-frequency fields to specific areas of the body. These basically act as a noninvasive method of creating a "slice" of the body. The resulting image reveals all the various tissues in different shades so that doctors can spot any abnormalities that may need to be investigated.