Electricity Around Us

ELECTRICITY
AROUND
US

Muhammad Aimin Zairil Bin Saad

MUHAMMAD AIMIN ZAIRIL BIN SAAD

Ossas Publications Sdn. Bhd.
No9, Jalan Indera,
01234, Bukit Tajam, Pulau Pinang
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Fax: 03 1234567

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Acknowledgement

All praise and appreciation to God for providing
me with the courage and strength to finish this
lesson book.

I'd want to express my gratitude to my lecturer,
Madam Norezan, because this lesson book could
not have been completed successfully without
her guidance. She constantly provides guidelines
and assistance in order to achieve a positive end
of this lesson book titled 'Electricity Around Us'
Form 5 chapter 3: Electricity.

Finally, I was overwhelmed by my classmate's
assistance. Thank you very much for continuously
providing me good feedback so that I could finish
my lesson book.

TABLE OF CONTENT

CHAPTER 1:

Current and Potential Difference

topic page
learning outcome chapter 1 1
2
electric field 3
electric field strength 4
Effects of electric field 4

electric current

CHAPTER 2: page
5
Resistance 6
7
topic 8
learning outcome chapter 2 9
10
ohm's law
Factors that affect the resistance of a wire

resistivity of a conductor
Exercise

reference

LIST OF TABLES
AND FIGURES

Tables and figures page
2
Figure 1.1: Electric field pattern 2
3
Figure 1.2: Electric force acting on positive and 3
negative charge 4
6
Figure 1.3: Particle with positive and negative 6
charge 7

Figure 1.4: Formula for electric field strength 8

Figure 1.5: The effects of an electric field on a
candle flame

Figure 2.1: Graph of V against I

Figure 2.2: Circuit in series

Table 2.3: Comparison of graphs of V against I
for an ohmic and a non-ohmic conductor

Table 2.4: Comparison between non-conductors,
semiconductors, conductors and
superconductors

Current and
Potential Difference

Learning Outcome

Student should be able to:
Explain electric field
Define strength of electric field, E
Explain behaviour of charged
particles in an electric field
Define electric current
Define potential difference, V

1

1. Current and Potential Difference

What is Electric Field?

Electric field is the region around
a charged particle where any
electric charge in the region will
experience an electric force.

Electric Field Positive charges does not
experience electric force (not
repelled by +) because it is
outside the electric field.

Figure 1.1: Electric field Negative charges experience
pattern electric force (attracted to +)
because it is inside the electric
field.

HOW TO DRAW • Arrow goes out
ELECTRIC FIELD? of positive charge
• Arrow goes into
Figure 1.2: Electric force acting on negative charge
positive and negative charge • Lines cannot cross
each other
• Like charges repel
• Opposite charges
attract

2

Teacher. What is electric
field strength ?

Electric field strength is
electric force acting on a
unit positive charge
placed at the point.

REPULSIVE FORCE

qF

Fq

Figure 1.3: Particle with positive ATTRACTIVE FORCE
and negative charge

The S.I unit for
charge is

coulomb (C)

E = electric field strength, NC-1
F = electric force, N
q = quantity of electric charge, C

Figure 1.4: Formula for electric 3
field strength

What is the effects
of an electric field
on a candle flame?

Figure 1.5: The effects of an
electric field on a candle flame

When the power supply is switched on, the candle
flame will spread out between the twometal
plates. The spread of the flames towards the
negatively charged metal plate is greater than
towards the positively charged metal plate.

The heat from the candle flame causes the air to
ionise to form positive ions and negative ion

The negative jons will be altracted to the
positively charged metal plate while the positive
ions to the negatively charged metal plate.

Positive ions have larger mass and size compared to
negative ions. Therefore, the spread of Names
towards the negatively charged metal plate is greater
than towards the positively charged metal plate.

What is Electric An electrical equipment can
Current? only function if current
Rows in a complete electric
circuit. Current, I is the rate
of flow of charge, Q in a
conductor.

4

Resistance

Learning Outcome
Student should be able to:

Compare and contrast ohmic and
non-ohmic conductor.
Solve problems involving
combination of series and parallel
circuits.
Define resistivity of wire, ρ.
Describe factors that affect
resistance of a wire through
experiments to conclude R=ρl/A.
Communicate about applications of
resistivity of wire in daily life.
Solve problems involving the
formula of wire resistance.

5

2. Resistance

Ohmic Conductor and Let's recap
Non-Ohmic Conductor Ohm's Law.

A conductor which
obeys Ohm's Law is
called an ohmic
conductor whereas a
conductor which does
not obey Ohm's Law is
called a non-ohmic
conductor.

Figure 2.1: Graph of V Figure 2.2: Circuit in
against I series

Potential difference flowing
through a conductor is directly
proportional to the electric
current when the temperature
and other physical properties
are kept constant

6

Table 2.3: Comparison of graphs of V against I for an ohmic and a non-ohmic
conductor

Type of conductor Ohmic conductor Non-ohmic
conductor

Graph of V against I



Relationship between V is directly V increases with I
V and I proportional to I Increases
Increases
Rate of increase of Constant
voltage

Resistance Constant

Factors that affect the
resistance of a wire

l = length of the wire, m
( l increase, R increase )



A = cross-sectional area of the

wire, m2
( A increase, R decrease )



= resistivity of the wire, Ωm

( ρ increase, R increase )

7

What is resistivity
of a conductor, ρ?

Resistivity of a conductor, ρ is a measure
of a conductor’s ability to oppose the flow
of electric current.
Unit for resistivity of a conductor, ρ is
ohm-meter (Ω m)
Resistivity of a conductor, ρ depends on
the temperature and the nature of the
conductor material.

Heating Element • heating plate is a heating element
• high resistivity, melting point and is
durable

Connecting Wire • connecting wire uses copper (low
resistivity)
• avoid heating up too quickly when
current flows

Table 2.4: Comparison between non-conductors, semiconductors, conductors and superconductors

Non-conductor Semiconductor Conductor Superconductor

does not conducts conducts conducts
conduct electricity better electricity electricity
electricity and than an insulator without any
good insulator but not as good as low resistance
resistivity

a conductor zero resistivity

Examples: at critical
iron and
highest resistivity between carbon temperature
resistivity a non-conductor
and a conductor Example:
caesium at a
Example: plastic Examples: silicone temperature of
and wood and germanium 1.5 K or lower

8

EXERCISE

1.Define current and potential difference.
2.What is an electric field?
3.What happen to resistance if the rate

of increase of voltage constant?
4.What are the factors affecting

resistance of a wire?
5.State the relationship between each

factors with resistance of a wire.

9

reference

1. Koay Kheng Chuan, C. S. (2020). DUAL LANGUAGE
PROGRAMME PHYSICS FORM 5. Malaysia: PENERBIT
BESTARI SDN. BHD.

2. Slavko Vujević, T. M. (2011). The difference between
voltage and potential difference. IEEE Xplore, pp.1-10.

3. T.J. Ericson, (1968).“The concepts of potential
difference, voltage and E.M.F.I,” Physics Education,
vol. 3, pp. 238-241.

4. F. Reif, (1982).“Generalized Ohm’s law, potential
difference, and voltage measurements,” Am. J. Phys.,
vol. 50, no. 11, pp. 1048-9.

5. H.W. Nicholson, (2005).“What does the voltmeter
read,” Am. J. Phys., vol. 73, no. 12, pp. 1194-6.

6. E. Lanzara and R. Zangara, (1995).“Potential
difference measurements in the presence of varying
magnetic field,” Physics Education, vol. 30, no. 2, pp.
85-89,

10