![Electromagnet.](https://img-aws.ehowcdn.com/360x267p/photos.demandstudios.com/getty/article/110/160/96683311.jpg)
Electromagnets are fundamentally useful devices, producing controllable amounts of magnetic force from an electric current. The strongest magnets are cool, have many turns of wire in their coils and use large amounts of current.
Description
![Photo Credit: Jupiterimages/Photos.com/Getty Images Insulated wires.](https://img-aws.ehowcdn.com/600x600p/photos.demandstudios.com/getty/article/251/167/87825048.jpg)
An electromagnet is usually a coil of insulated wire wound around an iron core. It becomes magnetized when you run an electric current through it and loses magnetism when the current stops.
Turns
![Photo Credit: Hemera Technologies/PhotoObjects.net/Getty Images Pieces of a clock with electromagnet and coil.](https://img-aws.ehowcdn.com/600x600p/photos.demandstudios.com/getty/article/178/32/87517629.jpg)
To make an electromagnet stronger, you can wind a coil with more turns of wire. The number of turns multiplied by current in amperes gives ampere-turns, a factor that determines magnet strength.
Current
![Photo Credit: Ivan Mikhaylov/iStock/Getty Images Wires coming through walls.](https://img-aws.ehowcdn.com/600x600p/photos.demandstudios.com/getty/article/108/216/153859661.jpg)
Generally, a magnet’s strength increases with greater electric current. At a certain point, the magnet will saturate, reaching a maximum strength.
Core
![Photo Credit: Andrey Kuzmin/iStock/Getty Images Iron metal.](https://img-aws.ehowcdn.com/600x600p/photos.demandstudios.com/getty/article/94/75/140088435.jpg)
An electromagnet will be stronger if you wind the wire turns around a metal core. The best metals are typically ferrous, or iron-bearing.
Temperature
![Photo Credit: Jupiterimages/Photos.com/Getty Images Liquid nitrogen.](https://img-aws.ehowcdn.com/600x600p/photos.demandstudios.com/getty/article/178/182/87806744.jpg)
The current-carrying ability of wire improves with very low temperatures. The strongest magnets are made of superconductors cooled with liquefied nitrogen or helium.
References
About the Author
Chicago native John Papiewski has a physics degree and has been writing since 1991. He has contributed to "Foresight Update," a nanotechnology newsletter from the Foresight Institute. He also contributed to the book, "Nanotechnology: Molecular Speculations on Global Abundance." Please, no workplace calls/emails!
Photo Credits
Robert Kyllo/iStock/Getty Images