File 42957
Transcript of File 42957
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A paperclip is attracted to the ends of a bar magnet
The paperclip is made of steel.
The arrow shows the force on the paperclip.
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Representing forces with arrows
The magnet also is pulled towards the paperclip.
The two forces are the same size
and in opposite directions.
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2 magnets
These ends attract
These ends push apart – (repel)
There are two sorts of magnetic poles.
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Making a compass When a magnet is hung
up one end will point North. so it lines up
North/South
The same end always points North
The end that points North is called the north seeking pole
N S
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Using a compass to find directions A compass needle always points to
the Earth’s North Pole.
Some birds use the Earth’s magnetism to find directions.
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The north pole repels the north pole of the other magnet.
You can feel the magnets pushing apart.
This is called repulsion
Note - south poles also repel each other
S N S N
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Something very new !
• A computer that will stay booted up when you switch it off – it will be on sale in a few year’s time.
• It will have memory called MRAM and use special magnets !
(Magnetoresistive Random Access Memory)
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What have we learned? Magnets will attract magnetic materials
iron and steel Magnets have two sorts of poles
north and south Magnets repel each other as well as
attract similar poles repel opposite poles attract
A compass is a little magnet The Earth is like a magnet
compasses are used to find directions Special magnets are used in computers
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It moves !
A motor causes movement.
An electric current and a magnetic field can make a simple motor.
magnet + electric current movement
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Very tiny motors can be made When the drawer for a CD opens and
closes a tiny motor makes it move A tiny motor moves the camera lens when
the camera is switched on Many small toys have motors in them
robots, Artificial limbs can use tiny motors to act
like muscles