Page 26 - Physics_Form_2

Physics for Secondary Schools

to the earth. Equally, a positively charged (b) How does the interaction
conductor can gain electrons from the between the comb, hair, and
ground, driven by the potential difference. If paper illustrate the principles
a wire connects two conductors at different of static electricity?
potentials, electrons will flow between 3. (a) Why do TV screens become
them until they reach the same potential, dusty after a while? Discuss.
FOR ONLINE READING ONLY
resulting in equal average potential energy (b) Explain any two applications
for the free electrons in both conductors. of electrostatics and hazards of
Typically, electrons move from areas of electrostatics
low potential to high potential as shown 4. If you are given two metal spheres
in Figure 1.25. standing on insulator stands and a

positively charged rod, explain how
High potential Low potential you can charge the two metal spheres
Electron flow
with equal and opposite charges by
induction.

Figure 1.25: Flow of electrons 5. (a) How can a charged leaf
electroscope be neutralised?
Exercise 1.1
(b) An object with an unknown
1. Explain why: charge is brought close to the
(a) Nylon clothes crackle as you electroscope. The leaves of
undress. the electroscope come closer
(b) Petrol road tankers usually have together. Does the object have
a long metal chain that hangs a positive or a negative charge?
down and touches the ground. Explain.
(c) Some clothes tend to cling to
the body of a person. Capacitors
(d) It is possible for an air passenger A capacitor is a device used to store
to get an electrical shock when
the passenger touches the knob electric charge. It consists of two
of the toilet door in a high- electrically conductive plates separated
altitude flying aeroplane. by an insulator material. The shape
2. Children playing with a plastic comb of a capacitor can be square, circular,
and some pieces of paper notice rectangular, or cylindrical. Insulators can
that the paper pieces are attracted be ceramic, plastic film, air, paper, mica,
to the comb after it has been rubbed or liquid gel. The insulating material
through their hair. between the conductive plates is called a

(a) Explain the concept of charge dielectric material. When a power source
transfer in this scenario. is connected across plates, one plate is

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Student’s Book Form Two

Physics Form 2 Final.indd 20 25/10/2025 10:25