Page 109 - Physics Form 5 KSSM_Neat

Current can flow from one point to another due to a CHAPTER 3
potential difference between the two points in a circuit. The History
potential difference, V between two points in an electric field is Electricity
the work done, W in moving one coulomb of charge, Q from
one point to another.

KEMENTERIAN PENDIDIKAN MALAYSIA
W E
V = or V =
Q Q
Alessandro Volta was an
where V = potential difference Italian physicist who invented
W = work done the voltaic pile, the first
E = energy transferred chemical battery. The unit of
Q = the amount of charges flowing volt was named in his honour
to recognise his contribution in
The S.I. unit for potential difference, V is joule per coulomb the field of electricity.
(J C ) or volt (V).
–1
The potential difference is 1 V if the work done to move 1 C Info
of charge from one point to another is 1 J.
Charge of an electron,
e = 1.6 × 10 C
–19
Therefore,
1 C = 1
1.6 × 10 –19
= 6.25 × 10 electrons
18
Formative Practice 3.1

1. Define current and potential difference.

2. What is an electric field?

3. Figure 3.11 shows an electronic advertisement board. The
current flowing is 4.0 × 10 A. What is the number of
–2
electrons flowing in the circuit when it remains switched
on for 3 hours?

4. A bulb labelled 3.0 V, 0.2 A was lit for 1 hour. Calculate:
(a) the electric charge
(b) the energy generated
Figure 3.11
5. An electric charge of 900 C flows through a metallic conductor in 10 minutes. Calculate
the current.

LS 3.1.5 99