What Are the Uses for Electromagnets?
Electromagnets take advantage of the ability of electrical currents to induce a magnetic field. More controllable than ferrous magnets, electromagnets allow for rapid manipulation and even the switching on and off of a magnetic field. Electromagnets are found in many kinds of technology, including motors, loud speakers and recording devices.
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History
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The electromagnet was first discovered in 1820 by the Danish scientist Hans Orsted when he realized that electrical currents can generate a magnetic field. The electromagnet was formally invented by William Sturgeon three years later. The first electromagnet was was a horseshoe-shaped piece of iron that was wrapped 18 times by copper wire. Strugeon demonstrated the strength of his invention by showing that it could lift up to 9 lbs. with the use of a battery.
Function
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One of the advantages of an electromagnet is that the magnetic field can be altered by manipulation of the current that is passing through the device. As current passes through, it generates a magnetic field according to the right hand rule, which can be visualized by taking your right hand and pointing the thumb out in the direction of the current. The direction that can then be made by curling the fingers around will show the direction of the magnetic field.
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Considerations
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Many times in order to organize and control the field, the wire with the current will be wound into a coil. This coil can be either helical in shape (called a solenoid) or be bent into a donut shape, causing the ends to meet. This latter form is a toroid. As the current passes through, small elements within the wire, called magnetic domains, will align with the generated field, causing the field to be reinforced. Sometimes the material will have a permanent realignment, causing the core to have retained magnetic properties.
Types
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Electromagnets are often defined by the materials they contain and the special modifications needed to generate different forces. Many electromagnets are augmented by having iron or other naturally ferromagnetic material within the core, which generates a maximum force of 1.6 Teslas (the scientific unit of magnetic strength) per unit of area. In the event the greater fields are needed, the techniques of high field electromagnets, which use modified electromagnets will generate greater forces.
Effects
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Electromagnets are most commonly seen in electrical devices. They form a critical part of motors and generators, using the force of the magnetic field to generate power and current. They can also be used for sonic purposes in electric bells and loudspeakers. Electromagnets can also be used to record material onto cassette tapes, VCR tapes and hard drives. Finally, high powered electromagnets can be used for medical imaging and particle accelerators.
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