Page 22 - Physics_Form_2
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Physics for Secondary Schools
on the electroscope can be determined by
Charged testing using the charged glass rod. When
ebonite
rod a positively charged glass rod is brought
near the brass cap, positive charges on the
cap are repelled towards the brass plate.
Therefore, the plate becomes positively
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charged. This causes the leaf to collapse,
as shown in Figure 1.21.
Charged glass rod
Figure 1.20
3. Observe the leaf of the electroscope.
Note: If the leaf does not stay
diverged, bring the charged ebonite
rod in contact with a brass cap of
the electroscope until the leaf stays
diverged.
4. Remove the charged ebonite rod from
the brass cap of the electroscope and
observe what happens to the leaf of Figure 1.21: Testing a charged
the electroscope. electroscope by using a
5. Charge the glass rod by rubbing it charged glass rod
with a silk cloth.
6. Bring the charged glass rod close Charging an electroscope by induction
(not touching) to the brass cap Having learnt how to charge an object
of the electroscope. Note your by induction, the same method can be
observations. applied to charge a leaf electroscope.
In this process, a positively charged
electrophorus is advised.
Questions
(a) Explain your observation. Activity 1.8
(b) Why does the leaf collapse when a
glass rod is brought near the cap? Aim: To charge an electroscope by
induction using a positively
charged electrophorus
When the negatively charged rod is brought
into contact with the electroscope, the Materials: electrophorus, glass rod,
latter gets charged and the leaf diverges. ebonite rod, silk cloth or
It acquires a negative charge. The charge fur, leaf electroscope
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Student’s Book Form Two
Physics Form 2 Final.indd 16 25/10/2025 10:25
