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Physics for Secondary Schools
If two negatively charged materials or two
Activity 1.4 positively charged materials are brought
Aim: To verify the fundamental near each other, they repel. However, if
law of static electricity a positively charged object is placed near
a negatively charged object, the objects
Materials: 2 dry glass rods, 2 ebonite attract each other. This suggests that
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rods, thread, stand, silk unlike charges exert an attractive force
cloth, fur (cotton cloth) on each other, and like charges exert a
Procedure repulsive force on each other.
1. Rub a dry glass rod with a silk
cloth and suspend it using a piece Activity 1.5
of thread. Aim: To show charge
2. Bring a second charged glass rod separation in materials
close to the suspended one as shown
in Figure 1.9. Materials: woollen cloth, glass rod,
3. Record your observations. cotton fabric, plastic pen
or comb, string, retort
4. Repeat steps 1 and 2 using an ebonite stand
rod rubbed with fur.
5. Now, repeat the activity by bringing Procedure
a charged glass rod close to the 1. Hang a comb from a string tied to a
suspended charged ebonite rod and retort stand.
the charged ebonite rod close to the 2. Rub the comb with a piece of cotton
suspended charged glass rod. Record fabric, then hang it.
your observations. 3. Rub a glass rod with a piece of
woollen fabric, then hang it.
Questions 4. Bring the charged glass rod near but
(a) What did you observe? not touching the hanging charged
(b) What conclusion can you make from comb.
your observations? 5. Bring the piece of woollen cloth that
you used to rub the glass rod near
but not touching the hanging comb.
Thread
Suspended Questions
glass rod
Hand (a) Which material will become
positively or negatively charged in
steps 2 and 3? (Refer to Table 1.1.)
Glass rod (b) What did you observe in steps 4 and
5?
Figure 1.9: Verification of the fundamental
law of electrostatics (c) Discuss your results.
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Student’s Book Form Two
Physics Form 2 Final.indd 8 25/10/2025 10:25
