Page 17 - Physics_Form_2

Static electricity

body. Consider two metal plates X and Y, where plate X is positively charged while
plate Y is uncharged. Both plates are then placed on insulating blocks brought into
contact and then separated as shown in Figure 1.12.
Plate X Plate Y Plate X Plate Y Plate X Plate Y

FOR ONLINE READING ONLY
Separation

Insulator
(Initially chaged) (Initially unchaged) During contact After separation
Figure 1.12: Charging by contact

Testing the metal plates after separation Step 1: A negatively charged rod is
shows that, when a charged body is brought near the uncharged
brought in contact with an uncharged spherical ball. The free electrons
body, the same electric charges are from the sphere are repelled by
distributed among the two bodies. As the excess electrons on the rod,
a result, the initially uncharged body and they are shifted towards the
acquires charges of the same sign as the right. They cannot escape from
charges of the initially charged body. the sphere because the stand and
the surrounding air are insulated.
Charging by induction Step 2: These excess charges, called
Charging by induction is a method of induced charges, are released to
charging an object without actually the earth by touching the right
touching it with any other charged object. part of the sphere with a wire
Figure 1.13 illustrates the simple steps to and connecting the other part of
induce a charge by induction. the wire to the earth.
Step 3: The wire is disconnected.
Step 1 Step 2 Step 4: The negatively charged rod is
removed. A net positive charge
is left on the spherical ball.

Activity 1.6

Step 3 Step 4 Aim: To demonstrate the transfer
of conduction electrons in a
conductor by the induction
method
Materials: iron nail, string, plastic

Figure 1.13: Inducing a charge on comb, cotton cloth, glass
a spherical ball rod, woollen cloth

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Physics Form 2 Final.indd 11 25/10/2025 10:25