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Magnets from Mini to Mighty
By Kristen Coyne
Many of us believe our daily experience with magnets begins and ends on the refrigerator door. There’s that cute shot of the kids in the magnetized frame, the clip holding the grocery list, the realtor’s business card and the haiku composed of magnetized words.
In fact, those are just one of several types of magnets that span a broad range of sizes, shapes, materials, strengths and applications. You may not see them, but magnets are everywhere – in our car motors, phones, tape recorders, credit cards, stereo speakers and computers, to name just a few practical applications. That’s not even to mention the enormous – and enormously powerful – magnets used at the Magnet Lab and other research institutions.
Some magnets last lifetimes, others come and go in the blink of an eye. Some are multi-ton behemoths, others only visible through a microscope. Some are molded by nature, others by man. Magnets also span a vast range of possible magnetic field strengths.
PHYSICS FACTOID: Scientists believe the Earth's magnetic field is a result of convection currents in the planet's liquid outer core, which makes a good conductor because it is made up largely of iron. This is called a geodynamo.
On the following pages we’ll review the basic types of magnets. But remember that there are properties that all magnets have in common. They all exert a magnetic force on each other. They all have a south pole and a north pole (just like the Earth, which itself is a magnet); opposite poles attract, like poles repel. In all magnets, the magnetic field lines run from south to north, and these fields are what produce forces on other magnets that follow specific physical laws.
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