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Magnetism

inserted in the solenoid, and a large current
is passed through the wire. The number of Activity 3.5
turns of the wire is also increased. This is Aim: To magnetise a steel
an industrial way of making a magnet. The bar
solenoid produces an electromagnet that acts Materials: steel bar, battery,
like a bar magnet.
FOR ONLINE READING ONLY
switch, solenoid of
copper wire, iron
filings

Procedure
1. Test the steel bar for magnetic
properties by using iron filings.
2. Connect the battery to the
solenoid and the switch.
3. Place the steel bar inside the

Figure 3.21: Electric method of magnetisation solenoid as shown in Figure
3.23.
Polarity of a magnet can be determined by
the direction of the current. When looking at
the nail, the end that has current flowing in a
clockwise direction is the S pole. If it flows
anticlockwise, the end acts as the N pole. See
Figure 3.22 (a). This is the rule for magnetic
polarity. Also, a right-hand grip rule can be
used to indicate the polarity of the magnetised
material. The rule states that “if the fingers of Figure 3.23: Making a steel bar
the right hand grip the solenoid in the direction magnet
of the current, then the thumb points to the N 4. Switch on the current for 10
pole of the solenoid” as shown in Figure 3.22 seconds and then switch off.
(b). 5. Remove the bar from the

solenoid and test it again for
magnetism using the iron
filings.
Questions
(a) Why is the current switched on

(a) Rule of magnetic (b) Right-hand for only a few seconds?
polarity grip rule (b) What is observed when the
steel bar is brought near the
Figure 3.22: Rules of polarity iron filings?

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Physics Form 2 Final.indd 105 25/10/2025 10:26