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William Gilbert, an Englishphysician, first proposed in 1600that the earth itself is a magnet,and he predicted that the Earthwould be found to have magneticpoles.

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Magnets are Useful

They help make work easier. You

can find magnets in the lab, injewelry, for fishing, on the

construction site, in the kitchen, in

cars, radios, video recorders, andeven on the farm.

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Magnet Safety

Safety Note: Keep magnets away from

electronic devices such as computers,

watches, and clocks, as they can damagethese items even with brief contact.

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An unmagnetized substance

looks like

this

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While a magnetized substance looks

like this

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The ends of a magnet are where

the magnetic effect is the

strongest. These are called

poles. Each magnet has

2 poles 1 north, 1 south.

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Like poles repels !

Opposites attract!

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Poles of amagnet alwaysCome in pairs

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How to break a magnet:

1. Drop it

2. Heat itThis causes the domainsto become random again

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If you cut a magnet in half,

you get 2 magnets

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North Poles Cannot Be Separated from South

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Magnetic Fields

The region where the magnetic forcesct is c lled the m gnetic field

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What does a magnetic field look like?

Well, we cant see it for a start, but...

Small particles of iron filings are pushed into

patterns by a magnetic field. If we sprinkle iron

filingson a piece of paper over a magnet we can

see...

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Sprinkle iron filings around a magnet,then you will be able to see the magnetic field.

Place white card over the magnet

and Sprinkle iron filings on a card.

Tap the card gently with a pencil and observe the pattern.

Bar Magnet

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What does a magnetic field look like?

The lines of force are very

close together here the field

is very strong.

The lines of force are further

apart here the field is weaker.

A line of force links one pole of a magnet to the other pole.

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Magnetic field of

Horseshoes magnet

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Magnetic field ofBar magnet

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The pattern and thedirection of a magnetic field can be

mapped using plotting compass.

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Compasses are place around the bar magnet

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The compass needles show the direction of force inMagnetic field.

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lets see how you

doing so far

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The Earth is a magnet:Magnetic South Pole

Magnetic North Pole

It exerts magnetic forces

and is surrounded by a

magnetic field that isstrongest near the

North and South

magnetic poles

Geographic North Pole

Geographic South Pole

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We use the Earths magnetic field to find direction.

The needle of a compass always points toward the

magnetic south pole.

We call this direction North (remember, opposites attract)

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The sun has a magnetic field, too.

It extends far above the suns

surface.

Other planets in the solar

system also have these

magnetic fields

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