Magnetism

Magnetic ForceInteractions of Forces and Motion

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Magnets have been known for centuries.Magnets have been known for centuries.The Chinese and Greeks knew about the The Chinese and Greeks knew about the “magical” properties of magnets. The “magical” properties of magnets. The ancient Greeks used a stone substance ancient Greeks used a stone substance called “magnetite.” They discovered called “magnetite.” They discovered that the stone always pointed in the that the stone always pointed in the same direction. Later, stones of same direction. Later, stones of magnetite called “lodestones” were magnetite called “lodestones” were used in navigation.used in navigation.

What is Magnetism?What is Magnetism?Magnetism is the force of attraction or repulsion of a magnetic material due to the arrangement of its atoms, particularly its electrons.

Will these items be attracted to a magnet?

yes no yes no yes no

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Were you correct? Why were these things attracted to the magnet?

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What will happen when the ends of the two bar magnets are placed close together?

What will happen when the ends of the two bar magnets are placed close together?

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The North and South poles of the magnet are attracted to one another.

Like poles of the magnet are not attracted, or repel one another.

If you cut a magnet in If you cut a magnet in half,half,

you get 2 magnets!you get 2 magnets!

An unmagnetized substance looks likeAn unmagnetized substance looks likethis…this…

While a magnetized substance looksWhile a magnetized substance lookslike this…like this…

How to break a magnet:

1. Drop it

2. Heat it

This causes the domains to become random again!

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These magnets are attracted to one another.Draw these magnets and label their poles?Explain your drawing.

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William Gilbert, an English physician, first proposed in 1600 that the earth itself is a magnet, and he predicted that the Earth would be found to have magnetic poles.

The Earth is a magnet:The Earth is a magnet:

Magnetic South Pole

Magnetic North Pole

It exerts magnetic forces and is surrounded by amagnetic field that is strongest near theNorth and South magnetic poles

Geographic North Pole

Geographic South Pole

The sun has a magnetic field, The sun has a magnetic field, too. It extends far above the too. It extends far above the sun’s surface.sun’s surface.

Other planets in the solar Other planets in the solar system also have these system also have these magnetic fieldsmagnetic fields

The Earth’s magnetic field extends far into space. It is called the “magnetosphere.”

When the magnetic particles from the sun, called “solar wind”, strike this magnetosphere, we see a phenomenon called…

The Aurora Borealis in the Northern HemisphereThe Aurora Borealis in the Northern Hemisphere

And the Aurora Australis in the Southern HemisphereAnd the Aurora Australis in the Southern Hemisphere