What is an Electromagnet?

Michael Pollick
Michael Pollick

An electromagnet works on the principle that an electric current not only allows electrons to flow in a circuit, but also generates a small magnetic field. When a wire carrying electricity is coiled, the magnetic field becomes even stronger. Iron or steel objects surrounded by this coiled electric wire also become magnetized. This combination of electronic energy, coiled wiring and conductive metal object forms the basis of the device.

A small electromagnet.
A small electromagnet.

It may be easier to think of an electromagnet as an electron magnet, not an electric magnet. What is relevant is the free flow of electrons in a circuit and their effects on the wire carrying them. It's possible to demonstrate the basic principles using a supply of bare copper wiring, a D-size chemical battery, and an iron or steel nail.

Electromagnets are used in electric motors.
Electromagnets are used in electric motors.

The reaction between the metals and acid in chemical batteries causes a lot of free electrons to collect near the negative post (-), generally the end with a slight depression. If someone connects the negative end of the battery with the positive post (+), all of those electrons will flow through the wire towards the positive post and eventually make their way back to the negative end. Since there is nothing blocking their path along the wire, such as a light bulb or motor, the electrons will soon stop flowing and the battery will "die."

The flowing electrons do more than run through the wire in a circuit, however. The motion of the electrons causes a slight magnetic field to form around the wire. This field is not especially strong as long as the wire remains straight, but coiling the wire in tight spirals will strengthen the magnetic field many times over as the wire's surface area is condensed.

The coiled wire can generate a measurable magnetic field which can affect a compass reading or small iron filings, but it still needs a means to focus all of the energy. This is where the iron or steel nail comes in. If the wire carrying the electrons is coiled tightly around a metal capable of being magnetized, the metal itself becomes an electromagnet. As long as current continues to flow through the coiled wire from the battery or other source of electricity, the metal core will have all the power and properties of a natural magnet, including positive and negative poles and the ability to attract or repel other magnets.

This ability to alternatively attract and repel other magnetic fields leads directly to the creation of an electric motor. The shaft of an electric motor is nothing more than coiled wires connected to a source of electricity. As the electromagnet alternates between positive and negative polarity, it is either attracted or repelled by permanent magnets surrounding it. This causes the shaft to spin rapidly in one direction and allows the motor to perform work based on that motion.

Electromagnets can affect the reading of compasses nearby.
Electromagnets can affect the reading of compasses nearby.
Michael Pollick
Michael Pollick

A regular wiseGEEK contributor, Michael enjoys doing research in order to satisfy his wide-ranging curiosity about a variety of arcane topics. Before becoming a professional writer, Michael worked as an English tutor, poet, voice-over artist, and DJ.

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Discussion Comments


Would the principles work underwater without any shock hazard to organisms nearby?


I need to know how you make a motor with a coiled wire or electromagnet that makes a compass move.


Do we need any coding for the working of electromagnets through microprocessors?


how can we use electromagnets in producing electrical energy?


How are electromagnets made?


thanks for this great knowledge.


This was a wonderful experience and it really inspired me to come up with my very own design! thank you so so so very much for this wonderful page.


Electromagnet Inquiry: I want to do a science experiment and I need to know how many times in a minute and/or how many times a second can an electromagnet can be turned on and off. Does it reach full power when on for short durations.

Thank you -- John Buckingham


electromagnets are even found in electronics


how do we make an electro-magnetic generator?


only solid conductors is good for electro magnet or Liquid also have that property?


does iron strengthen electromagnets? not inside the coil, but magnetized to the iron inside? please respond soon, i need this for a science report.


Thank you so much for the information. It was really helpful for my son's science fair project. Thanks again.


might be fun.

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