5.82. Why Earth Is a Magnet http://www.ck12.org
5.82 Why Earth Is a Magnet
- Describe how Gilbert discovered that Earth is a magnet.
- Relate Earth’s inner structure to its magnetic field.
Did you ever see a globe like this one? Magnets in the globe and its stand repel each other, allowing the globe to
hover in midair. The globe is a good model for Earth the magnet.
Earth the Magnet
Like the real Earth, the globe pictured above is a magnet. Amagnetis an object that has north and south magnetic
poles and a magnetic field. The magnetic globe is a modern device, but the idea that Earth is a magnet is far from
new. It was first proposed in 1600 by a British physician named William Gilbert. He used a spherical magnet to
represent Earth. With a compass, he demonstrated that it the spherical magnet causes a compass needle to behave
the same way that Earth causes a compass needle to behave. This showed that a spherical magnet is a good model
for Earth and therefore that Earth is a magnet.
Q:Can you describe Earth’s magnetic poles and magnetic field?
A:Earth has north and south magnetic poles. The North Pole is located at about 80 degrees north latitude. The
magnetic field is an area around Earth that is affected by its magnetic field. The field is strongest at the poles, and