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Magnetism:
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The objects which attract or repel magnetic materials are called magnets.
Magnets have two poles: North (N) and South(S)
When we hang a magnet on a string, the end shows the North direction of Earth is called the North-seeking pole
(North pole) and the end shows the South direction of Earth is called the South-seeking pole (South pole).
Like poles repel each other whereas the Unlike poles attract each other.
Making magnets:
Magnets can be made from steel or iron by the following methods;
1. Stroking Method:
- Steel is used in this method
- end of the steel bar, where the North of the
magnet starts to stroke becomes North pole.
2. Electricity Method:
- iron nail, copper wire and battery are used in this method.
passes through the coil of wire, the iron nail
magnetised. This is called an Electromagnet.
the electromagnet can be increased by:
the number of turns of the coil
the current or voltage.
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Destroying Magnetism:
steel or iron can be demagnetised by the following methods;
2. Heating
current through the iron nail.
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Magnetic field:
The space around a magnet where the magnet can attract or repel
magnetic materials is called Magnetic field.
The Magnetic field lines:
- show the direction of the magnetic force at each point.
- never cross each other.
- are more near the poles of the magnet. (So that the poles have
more magnetic strength)
- start from North pole and end at South pole.
- as the current
becomes
- The strength of
i. increasing
ii. Increasing
A magnetised
1. Hammering
3. Passing ac
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Like poles
Compass needle:
A compass needle shows the North-South
direction. It’s needle is a magnet which aligns
in the North-South direction.
Investigating a Magnetic field:
To draw a magnetic field we can use a compass needle.
Unlike Poles