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Force of Magnetism - Windows to the Universe

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With Explore the Planets, investigate the planets, their moons, and understand the processes that shape them. By G. Jeffrey Taylor, Ph.D. See our DVD collection.

# The Force of Magnetism

You may ask, how does the force of Magnetism work? The force of magnetism is directed from one pole to another. A pole can be described as the locus, or point, where lines of magnetic force converge.

Most simple magnets have two poles (that makes them "di-poles"), as shown in this picture. Planets can have more than two poles. The magnetic field "lines" illustrate where the force of magnetism is, and whether it is stronger (red) or weaker (blue).

##### This is an illustration of how magnetism works. Click on images for full size version (40K GIF)
For simple magnets, the force of magnetism works in the following way: When two magnets are brought together, the force will attract the two magnets together if the poles are opposite, that is if the pole of the first magnet is positive and the pole of the second magnet is negative. If that condition is true, the two magnets will be "forced" to stick together.
If two magnets of the same polarity are brought together, the force of magnetism will repel the two magnets from each other, and they cannot be made to stick together.

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## Planetary Magnets

The Earth is a good example of a planetary dipole, where the lines of force point in a direction out of the South (magnetic) Pole and into the North (magnetic) Pole. Planets can also show evidence of quadrupoles...more

## The Magnetic Field

The force of magnetism causes material to point along the direction the magnetic force points. This property implies that the force of magnetism has a direction. As shown in the diagram to the left, the...more

## The Earth's Magnetosphere

The Earth has a magnetic field with north and south poles. The magnetic field of the Earth is enclosed in a region surrounding the Earth called the magnetosphere. As the Earth rotates, its hot core generates...more

## Earth's Magnetic Poles

Earth has a magnetic field. If you imagine a gigantic bar magnet inside of Earth, you'll have a pretty good idea what Earth's magnetic field is shaped like. Of course, Earth DOESN'T have a giant bar magnet...more

## Earth's North Magnetic Pole

Earth has a global magnetic field that is approximately, though not exactly, a dipole field (like a bar magnet) with a north pole and a south pole. Earth's North Magnetic Pole (NMP) is not in the same...more

## Detecting Planetary Magnetism

A magnetometer is an instrument for measuring magnetic fields. Many spacecraft carry magnetometers to measure the magnetic fields around planets they orbit or fly by. When a spacecraft takes such measurements,...more

## Electricity and Magnetism

Electricity and magnetism are two closely related and very important topics within the science of physics. We use electricity to power computers and to make motors go. Magnetism makes a compass point North...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support!