Page 15 - Physics_Form_2

Static electricity

Charging objects Mechanism of charging by friction
A neutral object has the same number of When two insulating materials are
positive and negative charges, so they rubbed together, friction generates an
balance each other out. When you bring imbalance of electric charges. Electrons,
another neutral object close to it or touch which are negatively charged particles,
them together, nothing special usually are transferred from one object to
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happens because both objects have another. The object that loses electrons
balanced charges. becomes positively charged, while the

object that gains electrons becomes
However, if something causes one of the negatively charged. This transfer of
objects to have more positive or negative charge is governed by the principle of
charges than the other, this is called conservation of charge, meaning that the
an imbalance of charges. Creating this total charge before and after the rubbing
imbalance is known as charging an object.
process remains constant. For example,
when an ebonite rod is rubbed with fur,
There are different ways to charge objects: electrons move from the fur to the ebonite
(a) Friction: Rubbing two objects together
can move electrons from one object rod as shown in Figure 1.10. As a result,
to another. the fur becomes positively charged (due
(b) Contact (or conduction): Touching a to the loss of electrons), while the ebonite
rod becomes negatively charged (due to
charged object to a neutral object can the gain of electrons).
transfer electrons.
(c) Induction: Bringing a charged object
close to a neutral object can rearrange
the charges inside the neutral object,
even without touching.

These methods all involve moving
electrons to create an imbalance of
charges, which makes the object either
positively or negatively charged.

Charging by friction Figure 1.10: Process of rubbing
Charging by friction is the oldest method
of generating electric charge, and it plays Every day examples of charging by friction
a fundamental role in understanding static 1. Combing hair: When you comb your
electricity. This process occurs when two hair with a plastic comb, electrons
objects in contact are rubbed against each are transferred from your hair to
other, leading to the transfer of electrons the comb. This causes the comb to
from one object to another. become negatively charged, allowing

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Physics Form 2 Final.indd 9 25/10/2025 10:25