7.3 magnetism (offline note)

7.3 MAGNETISM

1. The characteristics of a magnet are:
(a) A magnet has two poles – the north and the south poles.
(b) The same poles repel, different poles attract each other.
(c) A free hanging magnet always points in the north-south

direction.
(d) A magnet can attract iron, steel, cobalt and nickel.
2. A magnetic field is a field of force surrounding a magnetic
body.

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• Magnetic filed: the area around the magnet
with magnetic force.

• Neutral point: space that does not have any
magnetic field.

The characteristics of magnetic field lines

1. The magnetic field lines begin from the north pole and end at
the south pole.
2. The magnetic filed lines are closer to one another where the
magnetic filed is stronger.
3. The magnetic field lines never meet or across.

Electromagnet

1. An electromagnet is a type of magnet that has
temporary magnetic effect when electric current
flow through it.

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• The direction of the
magnetic field depends on
the direction of the
current flowing in the
wire.

• It can be determined by
using a simple method
called ‘ right – hand grip
rule’.

Application of magnets and electromagnets in daily

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The needle of a compass uses a magnet to draw
to show the direction of the poles.

Credit cards and debit cards
have an electromagnetic strip
that stores information.

The electromagnet attached to Other examples :
a forklift is used to lift and Telephone
move objects like waste iron Electric bell
from one place to another at a
scrapyard.