20040 AC Science Year 4 Physical sciences

What are magnets? How do they work? - I
Read the text.
A magnet is any object or material, usually metallic, which produces an invisible
force called a magnetic field. This force allows it to attract some metals and to
attract or repel other magnets from a distance.
Two magnets, held close
together, will create pushing or
pulling forces on one another.
These forces are strongest at the
poles of the magnets. When the
same poles on two magnets are
held close together, the magnets
will push away from, or repel,
each other. Same (or like) poles
repel. When different poles of two
magnets are held close together,
the magnets will pull towards, or
A magnetic compass needle moves freely around a
pivoting point. One end of the needle always points
to the north, and the other end points to the south.
The ends are called the poles.
The poles of a magnet attract each other. The lines
of force of the magnetic field start at, and exit from,
the north pole. They end, or enter, at the south
pole. The lines of force are closer together and
stronger (concentrated) near the poles and further
apart at other places. The lines of force do not
cross each other and are shown on diagrams with
arrows which indicate the direction of the force.
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attract, each other. Opposite (or FF'
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unlike) poles attract.
Magnets can attract magnetic materials as well as other magnets. Magnetic
materials include iron, nickel, cobalt and steel.
Some magnets have stronger magnetic fields than others. Stronger magnets will
create bigger pushing or pulling forces. Magnets may also vary in shape and size.
A permanent magnet, such as a bar magnet, is magnetic all the time; its force
cannot be turned off. An electromagnet can be made by passing an electric
current through a coil of wire. The electromagnet stops acting as a magnet as
soon as the current is turned off.
Magnets have many uses including fridge magnets, doorbells, games, cupboard
door mechanisms, credit card strips, microphones and toys.
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CURRICULUM SCIENCE (Year 4)
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