Page 123 - Physics_Form_2

Magnetism

Just as with the compass needle, the pole 3. Push one end of the nail slightly
which points towards the north is the horizontally so that it rotates slowly.
north-seeking pole (N pole), and the other When the nail comes to rest, its tip
is the south-seeking pole (S pole). will be pointing toward the earth’s
MSP.
Activity 3.10 4. Place a piece of tape on the edge of
FOR ONLINE READING ONLY
the dish to mark this direction.
Aim: To demonstrate the presence 5. Push the nail slightly, then observe
of the Earth’s magnetic field
its orientation when it stops moving.
Materials: a nail or pin, water, bar Repeat this several times.
magnet, stopper (cork), water
dish Questions
Procedure Does the needle always point in one
1. Using the north pole of a bar magnet, direction? Why?
stroke a nail or straight pin from head
to tip 10 to 15 times. This magnetises If a bar magnet is suspended horizontally
the nail with a south pole (SP) at the from its centre, it will point to the north-
tip and a north pole (NP) at its head south direction. The bar magnet is free to
as shown in Figure 3.48. turn and lines up along the field lines of
the Earth’s magnetic fields.

Earth’s magnetic lines of force about a
bar magnet

The Earth’s magnetic field around the
NP SP equator consists of parallel lines that point
toward the north, as shown in Figure 3.50.
Figure 3.48 This forms a ‘uniform field’ in which the

2. Float a cork or rubber stopper in a direction and strength of the lines of force
dish with shallow water. Place the are constant.
nail on the cork as shown in Figure
3.49.

Figure 3.50: Earth’s field

The Earth’s magnetic lines of force

Figure 3.49 about a bar magnet are a resultant of two

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Physics Form 2 Final.indd 117 25/10/2025 10:27