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Physics for Secondary Schools

Charge distribution on a conductor
Induced charge resides on the surface of a conductor. Conductors appear in many
different shapes, such as spherical, pear-shaped and cylindrical surfaces. Charge
distribution on conductors depends on the shape of the conductor.

Charge distribution on the surface of a conductor
FOR ONLINE READING ONLY
The distribution of charges on a conductor depends on the shape of the conductor.
A proof plane and a gold-leaf electroscope can be employed to investigate this
phenomenon. This is accomplished by successively pressing the proof plane against
various regions of the surface of a conductor and then transferring the collected charge
to the electroscope. The extent to which the leaves of the electroscope diverge provides
a rough estimate of the amount of charge that has been transferred within a certain
region, which, in turn, offers insight into the surface charge density of the conductor,
as shown in Figure 1.41.

Charge
transferred by
proof plane
+ +
+ ++ + + +
+ + +
+ + +

–
– + +
Spherical Cylindrical Pear shaped

Figure 1.41: Testing charge distribution according to the shape of the conductor

The charge density of charged conductors (pear, spherical, cylindrical
of various shapes, such as spherical, and conical conductors
cylindrical, and pear-shaped, can be

tested. To examine the charge distribution Proof plane
on a conductor, carry out Activity 1.11.

Activity 1.11
Pear-shaped
Aim: To examine the distribution conductor Gold leaf electroscope
of charge through various Figure 1.42
conductors Procedure

Materials: proof plane, leaf 1. Charge a pear-shaped conductor.
electroscope, aluminium 2. Using a proof plane, touch the flat
foil, various conductors side of the conductor

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Student’s Book Form Two

Physics Form 2 Final.indd 30 25/10/2025 10:25