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What is an Electromagnet?

A small electromagnet.
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  • Written By: Michael Pollick
  • Edited By: Lindsay D.
  • Last Modified Date: 13 April 2014
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    Conjecture Corporation
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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.

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.

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."

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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.

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Discuss this Article

anon306055
Post 17

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

anon286954
Post 16

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

anon157496
Post 15

how can we use electromagnets in producing electrical energy?

anon85423
Post 12

How are electromagnets made?

anon62186
Post 9

thanks for this great knowledge.

anon51223
Post 8

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.

anon36918
Post 7

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

anon35824
Post 6

electromagnets are even found in electronics

anon35409
Post 5

how do we make an electro-magnetic generator?

kumaresh1881
Post 4

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

anon20733
Post 3

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

anon19260
Post 2

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

kennyli2
Post 1

might be fun.

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