How Is an Electromagnet Produced?

Hard Drive Electromagnetic Read-Write Head

An electromagnet is a magnet consisting essentially of a soft-iron core wound with a current-carrying coil of insulated wire. The current in in the wire magnetizes the core. An electromagnet can be turned on and off with a switch. Its simple design makes it highly versatile.

How is an Electromagnet Produced?

Waiting For Junkyard Electromagnet

The most common way to make an electromagnet is to wind insulated wire around an iron or steel core, such as a bolt or nail, and connect the bare ends of the wire to the terminals of a dry-cell battery. When current--generated by the battery--flows through the wire, a magnetic field is produced, and the core becomes magnetized. As long as current flows through the wire, the core will remain magnetized. When the power is removed, the magnetic field collapses and the core is no longer magnetized.

History of Electromagnets

Electromagnet at Work

A British scientist named William Sturgeon is on record as being the first to produce a working electromagnet using iron, copper wire and a battery, sometime between 1823 and 1825. In 1830, an American inventor, Joseph Henry, reproduced Sturgeon's first electromagnet on a more powerful scale. Henry transmitted electricity over a mile of wire that actuated an electromagnet and rang a bell on the other end. Sturgeon and Henry had laid the groundwork for the first telegraph.

Benefits of Electromagnets

The ability of an electromagnet to be energized and de-energized (turned on and off) makes it very suitable for intermittent use. An electromagnet can be turned on to pick up a load, move it and then be turned off by removing electric power. In addition, the magnetic strength can be varied by simply changing the amount of electrical current applied to the coil. The versatility of electromagnets makes them very adaptable. They can be used to lift tons of metal or interrupt current flow when used in circuit breakers.

Uses for Electromagnets

Electromagnets are used to lift and carry scrap metal and move cars around in junkyards. Electromagnets are also used for recording digital information in computer hard drives, tape recorders, VCRs and in TV cathode ray tubes. They are used in spacecraft propulsion systems to generate power. The medical field uses electromagnets for removing metal particles from eyes and for MRI (magnetic resonance imaging) procedures.

Considerations

Because of the relatively simple design of an electromagnet and its widespread applicability, electromagnets have improved the lives of people in countless ways. Although it's no longer considered a leading-edge technology, its pervasive use will continue.

References

• Making an electromagnet
• William Sturgeon
• History of electromagnet

Resources

• Electromagnets