power of a magnet

A Magnet’s PowersA Magnet’s Powers

Chapter 21

My Pals are Here! Science 3B © 2004 Marshall Cavendish International (Singapore) Private LimitedMy Pals are Here! Science 3B © 2004 Marshall Cavendish International (Singapore) Private LimitedYou are reminded that under the Copyright Act, it is an offence to reproduce or copy any part of this presentation without permission fromYou are reminded that under the Copyright Act, it is an offence to reproduce or copy any part of this presentation without permission from

Marshall Cavendish International (Singapore) Private Limited.Marshall Cavendish International (Singapore) Private Limited.

Magnetic MaterialsMaterials that are attracted to

a magnet are magnetic.



Examples of magnetic materials are metals such as iron, steel and nickel.

iron nails steel spoon and knife



Non-magnetic MaterialsMaterials that are not attracted to a magnet are non-magnetic.



Examples of non-magnetic materials are…

…metals such as gold, aluminium,

silver and copper.

gold brooch

copper container

aluminium earrings



…all non-metals such as plastic, wood, paper, glass and clay.



Every magnet has two poles, regardless of the

shape.Where do you think are the poles of these magnets?



Strong Ends of a Magnet

A magnet’s attraction is strongest at

its poles.



Poles of a MagnetA magnet that is allowed to turn freely will always come to rest in

the North-South direction.

South North

S NN S



How does a magnet help us find direction?



The pole that always points to the North is called the North-seeking

pole or N-pole.

The pole that always points to the South is called the South-seeking

pole or S-pole.

N-pole S-poleN S



NS N S

Like Poles Repel

When the same poles of two magnets are brought together, the magnets push one another away.



Unlike Poles Attract

N S N S

When the N-pole of one magnet is brought near the S-pole of another,

the magnets attract each other.



hammered

Magnets get weaker if they are…

dropped

heated



The more we care for our magnet, the longer it will last.



At a glance…

Magnetic materials are materials that are attracted to a magnet.

Examples are iron, steel and nickel.



At a glance…

Non-magnetic materials are materials that are not attracted to a magnet.

Examples are gold, aluminium, silver, copper and all non-metals.



At a glance…

All magnets have two poles.

A magnet’s attraction is strongest at its poles.A magnet that is allowed to turn freely will always come to rest in the North-South direction.



At a glance…

The pole that always points to the North is the North-seeking pole or N-pole.

The pole that always points to the South is the South-seeking pole or S-pole.



At a glance…

Like poles repel. Unlike poles attract.

Magnets get weaker if they aredroppedhammeredheated

power of a magnet

Technology

unlike poles

magnetic materials

magnetic materials

turn freely

poles repel

south direction

seeking pole

materials