Any substance which attracts
pieces of iron towards itself.
And always comes to rest in N-S
direction is known as a magnet.
The Property of a magnet to
attract things made up of Iron,
Cobalt or Nickel is known as
The area surrounding the magnet
in which magnetic force is exerted
to attract iron is known as
The magnetic lines of force
originate from the North Pole of a
magnet and end at its South Pole.
The ends of the magnet where the
magnetic force is concentrated are
called magnetic poles.
Each magnet has 2 poles : North &
There are 2 types of magnets :
1) Natural Magnets:
They have low magnetic power.
Eg : Magnetite, lodestone.
2) Artificial Magnets :
They have a strong magnetic power.
They are found in different shapes.
A natural magnet attracts certain
5. Alloys of any of the above
These materials are called Magnetic
1. They attract magnetic materials
2. A freely suspended magnet
always rests in N-S direction.
3. Like poles repel, Unlike poles
Permanent magnet Soft-iron bar
Permanent magnet brought Soft-iron bar becomes an
near to soft-iron bar induced magnet
In magnetic induction, an opposite pole is always induced.
– 2 unlike poles facing each other is observed during magnetic
S N S N
The “free poles” near the end of magnets repel
As time passes, the magnet becomes weaker
To prevent this weakening, bar magnets are
stored in pairs by using keepers
– 2 pieces of soft iron across the ends of the bar
Place the steel object inside a
coil of wire (a solenoid).
• Pass a direct current through
• A magnetic field is
produced on the solenoid.
•The steel rod is now placed
inside a magnetic field.
•When the current is turned off
the steel rod is found to be
–Wrap the fingers around
the coil form in the
direction of the current
flow in the solenoid.
– the thumb will point in
direction indicating the
end which becomes the N-
We know that at the centre of the Earth lies a
molten metallic iron rich core.
The outer portion of this core is molten.
We also believe that this core is spinning.
It is believed that the metals in the core have
many loosely bound electrons and that these
particles can conduct electricity.
It is this mass of moving electrons which
produces the magnetic field.
Think of the Earth as having a gigantic bar magnet buried
In order for the north end of the compass to point toward
the North Pole, you have to assume that the buried bar
magnet has its south end at the North Pole.
This method is derived from
applying the processes of
– Note the polarities of both the
permanent magnet & steel bar
that is to be magnetized
–This form of magnetism gained is
weak but permanent
Two permanent magnets are
used in this method.
– Note of the polarities of the
permanent magnets & their
induced ends of the steel bar
–This form of magnetism
gained is also weak but