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Q & A: Making a magnetic field

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Most recent answer: 10/22/2007
Q:
How is a magnetic field created?
- Joshua (age 9)
El Paso, Texas
A:
Hi Joshua,

Magnetic fields are created either by the motion of electrical charges, or by the alignment of the spins of charged particles, like electrons.

Each electron acts like a little bar magnet, but in most materials, all the electrons are arranged so that their magnetic fields point in opposite directions and cancel out. Some materials, like iron, have electrons whose spins do not cancel out with their neighbors, and even like to spin in the same direction as their neighbors. Many bar and horseshoe magnets are made out of iron. Some other materials and mixtures of materials can make even stronger magnets than is possible with just iron.

To make a stronger magnet still, you can wind a wire in a coil and pass current through it. The moving electrons in the wire will set up a magnetic field whose strength is directly proportional to how much current is going through the wire.

The earth has a magnetic field around it, which is made from flowing currents in the earth's core (there may even be some magnetized material too, where the spins are aligned).

You might want to search this site for many more answers about magnets.

Tom

(published on 10/22/2007)

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