ACE EDUCATION PHYSICS
O’LEVEL

Grade 10 − 12
GCSE, GCE

NSWANA CHING’AMBU

The Authorship and Career Network

+260976008283, +260972719373

i


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Copyright © 2021 by Nswana Ching’ambu

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Nswana Ching’ambu
asserts the moral right as an author

First edition
ISBN: 978-9982-913-18-8

ii


To the students
Ace Education Book Series aims at giving detailed material in the simplest way to help students
understand and recall information easily. The books also highlight the importance and application of each
topic in real life so that students can understand why they are learning the material, how the material relates to
or can be used in real life.
Ace Education Physics O’level consists of 33 units. Each unit begins with the introduction and overview
of the unit, and ends with the review questions and solutions. To fully benefit, students are advised to
cover everything in each unit considered. Students can also learn more from our social media platforms.
On these platforms, students can find additional information, ask questions or participate in helping other
students.
With full confidence, this book will help a number of students, not just by boosting their scores, but also to
understand Physics Ordinary Level.

Ace Education

About the author

Nswana Ching’ambu has a bachelor’s degree in Human Biology from the University of Zambia and Teaching
Methodology from Gideon Robert University. He has been lecturing Clinical Medicine courses at Gideon
Robert University for many years. He lectures Anatomy and Physiology, Medical Biochemistry and Nutrition,
and previously used to lecture Cellular Pathology and Basic Microbiology. He is the founder of Ace
Education and the author of Ace Education Book Series for O’Levels: Biology, Chemistry, Physics and
Mathematics.
+260967744388




iii


TABLE OF CONTENTS

UNIT 1: MEASUREMENTS……………………………………………………………………………...…..1
UNIT 2: SCALAR AND VECTOR QUANTITY……………………………………………………..….....7
UNIT 3: LENGTH……………………………………………………………………………………….…...12
UNIT 4: TIME………………………………………………………………………………………….…….18
UNIT 5: MASS AND WEIGHT……………………………………………………………………....…….23
UNIT 6: VOLUME AND DENSITY…………………………………………………………….....………30
UNIT 7: CENTRE OF GRAVITY………………………………………………………………………….37
UNIT 8: DISTANCE AND DISPLACEMENT………………………………………………….…………42
UNIT 9: SPEED AND VELOCITY……………………………………………………………….………..45
UNIT 10: ACCELERATION…………………………………………………………………….…………..49
UNIT 11: MOTION GRAPH…………………………………………………………………….………….54
UNIT 12: FORCE……………………………………………………………………………….……………64
UNIT 13: CIRCULAR MOTION……………………………………………………………..……………..73
UNIT 14: FORCE ACTING ON SPRING…………………………………………………………..……..75

UNIT 15: MOMENT OF A FORCE…………………………………………………………….…………78
UNIT 16: WORK, ENERGY AND POWER……………………………………………………..………..82
UNIT 17: SIMPLE MACHINE……………………………………………………………………………...93
UNIT 18: PRESSURE……………………………………………………………………………..………..105
UNIT 19: THERMAL PHYSICS………………………………………………………………..…………120
UNIT 20: TRANSFER OF THERMAL ENERGY……………………………………………...………..137
UNIT 21: HEAT ENERGY AND LATENT HEAT……………………………………………..………147
UNIT 22: WAVE MOTION…………………………………………………………………………..……154
UNIT 23: ELECTROMAGNETIC SPECTRUM……………………………………………………...…...161
UNIT 24: LIGHT………………………………………………………………………………………...….167
UNIT 25: SOUND WAVE…………………………………………………………………………...…….182
UNIT 26: MAGNETISM…………………………………………………………………….…………...…190
UNIT 27: ELECTROMAGNETIC INDUCTION…………………………………………………...……. 198
UNIT 28: STATIC ELECTRICITY…………………………………………………………………...….. 208
UNIT 29: CURRENT ELECTRICITY……………………………………………………….…………….214
UNIT 30: PRACTICAL ELECTRICITY……………………………………………………………….….231
UNIT 31: BASIC ELECTRONICS………………………………………………………………………...241
UNIT 32: ATOMIC STRUCTURE………………………………………………………………….……..251
UNIT 33: RADIOACTIVITY………………………………………………………………………………257

iv


1.0

MEASUREMENTS

Introduction
Everything around us is made up of matter. This book, your pen, clothes, shoes, food, a wire, a car, an airplane,
petrol, diesel, water and so on, are all matter. Some matter such as petrol, diesel and food store energy. When

petrol is burnt it releases energy. How does this energy interact with matter? For instance, burning petrol in a
car engine. The study of matter, energy and their interaction is called physics. In simpler terms, physics is the
study of how things around us work. For example, how a car moves, an airplane flies, an electric bulb lit, a
speaker works and so on.
Matter has different sizes. The size of this book is different from that of a pen, cellphone, computer, car, etc.
Therefore, to understand how things around us work, we need to have precise measurements of each object we
study. To have exact measurements, objects have to be measured. A physical quantity is anything that can be
measured. Length, time and temperature are few examples of things that can be measured and therefore are
physical quantities. When we measure an object, we obtain its size. However, size alone is not sufficient.
Imagine you go to buy a carpet for your room. Can it be adequate to say, “I need 5 carpets.” Likely not!
Therefore, to describe a physical quantity such as length, not only the size is needed but also the unit. For
example, 5 metres of carpet, 50 kilometre journey, 2 kilograms of sugar, 5 litres of cooking oil, 37 oC (degree
celcius), 10 hours 30 minutes and so on.

Specific outcomes
This unit covers the types of physical quantities, standard units and the importance of prefixes. By the end of
this unit, you will be able to:
❖ Define physics
❖ Define the following physics terminologies:
• Physical quantity
• Magnitude
• Unit
❖ State the seven base quantities
❖ Give examples of derived quantities
❖ Differentiate base and derived quantities
❖ Understand what SI units are
❖ State the seven SI units with their symbols
❖ Understand what prefixes are and how to use them

Measurements


1


MEASUREMENTS
1.1

QUANTITY
• Physics is the study of matter, energy and their interaction.
• It deals with physical quantities and motions of matter.
• A physical quantity is a quantity that can be measured. It is expressed by a magnitude with a suitable
unit.
• Magnitude is the size of a quantity, for example, 2, 150, 3, 10.
• Unit is the standard measure of a quantity, for example, s (second), m (metre), kg (kilogram).

❖ TYPES OF PHYSICAL QUANTITIES
1. BASE QUANTITY
• Base quantities are fundamental physical quantities.
• These quantities contain only one unit.
• There are seven base quantities: length, mass, temperature, time, current, amount of substance,
and luminous intensity.
2. DERIVED QUANTITY
• Derived quantities are quantities that consist of two or more base quantities.
• Therefore, they have a combination of units.
• For example, speed is a derived quantity. Speed is the total distance covered per unit time.
Therefore, it consists of two base quantities; length (distance covered) and time.
Types of physical
quantities
Examples


1.2

Derived quantities

Length
Time
Mass
Temperature
Current
Amount of substance
Luminous intensity

Volume
Density
Speed
Area
Force
Pressure

UNITS
• Unit is defined as the standard measure of a quantity.
• SI units (International System of the unit) are used as standardized units of measurements.
• There are seven SI units.
• The table below shows SI units and their symbols.
Base quantities
Length
Time
Mass
Temperature
Current

Amount of substance
Luminous intensity

2

Base quantities

Measurements

SI unit
Metre
Second
Kilogram
Kelvin
Ampere
Mole
Candela

Symbol
m
s
kg
K
A
mol
cd


1.3


PREFIXES
• Prefixes are multiples or decimals of ten.
• They are useful for expressing the size of physical quantities that are too large or small.
• The table below shows the common prefixes.
Prefixes
Mega
Kilo
centi
milli
micro
nano

Value
1 000 000
1 000
0.01
0.001
0.000 001
0.000 000 001

Form
106
103
10−2
10−3
10−6
10−9

Symbol
M

K
c
m
µ
n

Measurements

3


REVIEW QUESTIONS
1. What is physics?
A. The study of numeral values and their operation.
B. The study of matter, its composition, properties and interaction to form other substances.
C. The study of matter, energy and their interaction.
D. The study of living things.
2. Physics as a field of science deals with
A. properties of matter.
B. how matter forms a living thing.
C. physical quantities of matter and its motion.
D. all the above.
3. Magnitude is defined as
A. property of the physical quantity.
B. quality of the physical quantity.
C. standard measure of the physical quantity.
D. size of the physical quantity.
4. Unit is defined as the
A. Property of the physical quantity
B. Quality of the physical quantity

C. Standard measure of the physical quantity
D. Size of the physical quantity
5. All physical quantities have
A. Magnitude and unit
B. Magnitude and size
C. Quantity and quality
D. Quality and unit
6. Which of the following consists of base quantities.
A. Length, mass and speed
B. Length, mass and time
C. Time, mass and density
D. Mass, volume and speed
7. The following consists of derived quantities
A. Length, mass and speed
B. Length, mass and time
C. Time, mass and density
D. Force, volume and speed
8. The SI unit of time is
A. Second
B. Minute
C. Hour
D. Day
9. The SI unit of mass is
A. Gram
B. Kilogram
C. Metre
D. Kilometre
10. The SI unit of length is
A. Gram
B. Kilogram

C. Metre
D. Kilometre
4

Measurements


11. The SI unit of temperature is
A. Degree celcius
B. Kelvin
C. Mole
D. Ampere
12. The SI unit of current is
A. Candela
B. Kelvin
C. Mole
D. Ampere
13. The SI unit of amount of substance is
A. Degree celcius
B. Kelvin
C. Mole
D. Ampere
14. The SI unit of luminous intensity is
A. Candela
B. Kelvin
C. Mole
D. Ampere
15. Which of the following value is the same as 1000 seconds?
A. 10−3 ms
B. 103 ms

C. 10−6 ms
D. 106 ms

Measurements

5


SOLUTIONS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.

C
C
D
C
A

B
D
A
B
C
B
D
C
A
D

6

Measurements


2.0

SCALAR AND VECTOR
QUANTITIES

Introduction
Imagine you walked 50 m to the right and walked back 40 m to the left. What is the total distance you covered?
It’s 90 m (50 m + 40 m). How far are you positioned from the starting point? 10 m (50 m − 40 m). Why is there
a difference between the first question and the second question? The first question asked only about the size of
the distance covered. However, the second question asked about the size of distance and direction moved in
relation to the starting point. In physics, quantities that consider only the size are called scalar quantities while
quantities that consider both the size and direction are called vector quantities.

Specific outcomes

This unit covers scalar and vector quantities. By the end of this unit, you will be able to:
❖ Scalar quantity:
• Define a scalar quantity
• Give examples of scalar quantities
❖ Vector quantity:
• Define a vector quantity
• Give examples of vector quantities
• Differentiate scalar quantities and vector quantities
• Calculate addition and subtraction of vectors

Scalar and Vector Quantities

7


SCALAR AND VECTOR QUANTITIES
2.1

SCALAR QUANTITY
• A scalar quantity is a quantity that only has magnitude but no direction.
• Scalar quantities are indicated only by the size of the quantity.
• Examples of scalar quantities are length, time, mass, volume, density, distance, speed, area, pressure,
work and temperature.

2.2

VECTOR QUANTITY
• A vector quantity is a quantity that has both magnitude and direction.
• Vector quantities are indicated by the size and the direction of motion of the quantity.
• Examples of vector quantities are displacement, velocity, acceleration, weight, gravity, and force.


2.3

ADDING VECTORS QUANTITIES
• When adding vector quantities, consider both the magnitude and direction of motion of the quantity.
• If both vector quantities are moving in the same direction, the resultant vector is the sum of all vectors.
VR = V1 + V 2

•

where
VR is the resultant vector
V1 and V2 are individual vectors moving in the same direction

If vector quantities move in the opposite direction, the resultant vector is the difference between the
forward and backward vectors.
VR = V1 – V 2

where
VR is the resultant vector
V1 and V2 are individual vectors moving in the opposite direction

❖ EXAMPLES
Find the resultant vector of the following forces

❖ SOLUTIONS
1. VR = V1 + V2
= 1N + 3N
= 4N
3.


8

VR = V1 + V2 − V3
= 3N + 1N − 3N
= 1N

Scalar and Vector Quantities

2. VR = V1 − V2
= 1N − 3N
= −2N


REVIEW QUESTIONS
1. What is a scalar quantity?
A. A quantity that can be measured
B. A quantity that has both magnitude and direction
C. A quantity that has a unit
D. A quantity that only has magnitude but no direction
2. What is a vector quantity?
A. A quantity that can be measured
B. A quantity that has both magnitude and direction
C. A quantity that has a unit
D. A quantity that only has magnitude but no direction
3. A quantity that also considers the direction of motion of an object
A. Vector quantity
B. Scalar quantity
C. Magnitude
D. Unit

4. Which of the following is a scalar quantity?
A. Velocity
B. Gravity
C. Speed
D. Force
5. Which of the following is a scalar quantity?
A. Acceleration
B. Distance
C. Displacement
D. Force
6. Which of the following is a vector quantity?
A. Gravity
B. Length
C. Speed
D. Mass
7. Which of the following is a vector quantity?
A. Volume
B. Area
C. Mass
D. Weight
8. Two forces 10 N and 15 N are pushing an object in the same direction. What is the resultant force acting on
an object?
A. 25 N
B. 5 N
C. −5 N
D. 10 N
9. A 120N force and a 300 N force are acting on an object in the same direction. What is the resultant force?
A. 180 N
B. 200 N
C. 420 N

D. 550 N

Scalar and Vector Quantities

9


10. A forces 50 N and 30 N are acting on the same object. A 50 N force is pulling the object to the left while
a 30 N force is pulling an object to the right. What is the resultant force and direction of motion?
A. 80 N to the right
B. 80 N to the left
C. 20 N to the right
D. 20 N to the left
11. A bag of cement weighing 500 N is acted upon by an upward force of 720 N. What is the resultant force
and direction of motion?
A. 220 N upward
B. 220 N downward
C. 1220 N upward
D. 1220 N downward

10

Scalar and Vector Quantities


SOLUTIONS
1.
2.
3.
4.

5.
6.
7.
8.
9.
10.
11.

D
B
A
C
B
A
D
A
C
D
A

Scalar and Vector Quantities

11


3.0

LENGTH

Introduction

“How far is the journey?”, “How tall is the building?”, “How thick is the hair?”. What is common in all these
questions? The distance between two points. The first is about the distance from the start to the end of the
journey. The second is about the distance from the ground to the top of the building. The third is about the
distance between one side of the hair to the other. The distance between two points is called length. This unit
cover instruments commonly used to measure the length in physics and how to use them.

Specific outcomes
By the end of this unit, you will be able to:
❖ Define length
❖ State the SI unit of length, and other units
❖ Know the instrument used for measuring length
❖ Measuring tape and metre rule:
• Know how to read the metre rule
• State the causes of errors
❖ Vernier calipers:
• Know the parts of the vernier calipers
• Know how to read the vernier calipers
❖ Micrometer screw gauge:
• Know the parts of the micrometer screw gauge
• Know how to read the micrometer screw gauge

12

Length


LENGTH
3.1

LENGTH

• Length is defined as the measure of distance between two points.
• SI unit: metre (m); other common units used to measure length are centimetre (cm), kilometre (km).
• Instruments for measuring length.
1. Measuring tape
• A measuring tape measures long lengths.
• It is 1mm accuracy.
• Example of length measured; length of the classroom, width or height of the house.
2. Metre rule
• A metre rule measures medium lengths.
• It is 1mm accuracy.
• Example of length measured; length of the book, chair, desk.
3. Vernier caliper
• A vernier caliper measures short lengths.
• It is 0.1mm accuracy.
• Example of length measured; width of the pen, the diameter of the water tap.
4. Micrometer screw gauge
• Micrometer crew gauge measures very short lengths.
• It is 0.001 mm accuracy.
• Example of length measured; diameter of the hair, the thickness of a razor blade.
Correct reading:
12 cm
Wrong reading:

3.2

MEASURING TAPE AND METRE RULE
Wrong reading:
13 cm
11 cm
• How to use a metre rule

1. Put the zero mark at the end of an object.
2. Read the mark at the other end of an object.
• Causes of reading errors
5
10
20
0
15
1. Zero error: the value error due to not placing the
object at the zero mark of a ruler.
2. Parallax error: the value error due to the position of the eye when reading. The eye must be
vertically placed above the mark of the reading scale.

3.3

VERNIER CALIPER
• A vernier caliper consists of the main scale, vernier scale and two jaws.
• Object to be measured is put between jaws.
• The outer jaw is used to measure external diameters such as the diameter of a solid metal rod.
• The inner jaw is used to measure internal diameters such as the internal diameter of the water tap.

Length

13


❖

14


HOW TO READ A VERNIER CALIPER
i. Read the main scale by reading the mark on the main scale before the vernier scale's zero mark.
ii. Read the vernier scale by reading the mark on the vernier scale in line with the main scale. Then,
multiply the value of the vernier scale by 0.01cm.
iii. Add the main scale and vernier scale.

Length


3.4

MICROMETER SCREW GAUGE
• A micrometer crew gauge consists of a ratchet, thimble, sleeve, frame, spindle and anvil.
• The object to be measured is gripped between the anvil and the spindle using the ratchet.

❖ HOW TO READ A MICROMETER SCREW GAUGE
i. Read the main scale by reading the mark on the sleeve before the thimble.
ii. Read the circular scale by reading the mark in line with the horizontal line of the main scale. Then,
multiply the value by 0.01 mm.
iii. Add the main scale and the circular scale.

Length

15


REVIEW QUESTIONS
1. Which of the following devices can be used to measure the thickness of a banknote?
A. Micrometer screw gauge
B. Vernier caliper

C. Metre rule
D. Measuring tape
2. Vernier caliper measures the
A. Diameter
B. Thickness
C. Depth
D. All the above
3. Inner jaws of vernier caliper are used to measure
A. Thickness
B. Internal depth
C. Outer diameter
D. Internal diameter
4. Which instruments can be used to accurately measure a piece of wire about 1m long and 4mm in diameter.
A. Metre rule for length; vernier caliper for diameter
B. Metre rule for length; micrometer screw gauge for diameter
C. Metre for both length and diameter
D. Vernier caliper for length; micrometer screw gauge for diameter
5. The figure below shows the reading on a vernier caliper.

A. What is the reading on?
i. main scale
ii. vernier scale
B. What is the overall reading of a vernier caliper?
C. After zeroing the instrument it read +0.02cm. What is the actual reading of the object measured?
6. The figure shows the reading of a device used to measure the thickness of the material.

A. What is the name of a device?
B. What is the thickness of the material?
C. What are some of the precautions to be taken when using this device?


16

Length


SOLUTIONS
1.
2.
3.
4.

A
D
D
B

5. A. i. 6.3cm
ii. 0.05cm
B. 6.35cm
C. 6.33cm (6.35cm − 0.02cm)
6. A. Micrometer screw gauge
B. 4.11mm
C. Precautions
• The device should be dry and clean
• The device should be zeroed
• Avoid over tightening the thimble

Length

17



4.0

TIME

Introduction
“The event will commence in the afternoon and end in the evening.” What physical quantity can be used to
measure the period of occurrence of events? It’s time! Time is a physical quantity used to tell the progression
of events.
How was time measured in ancient times? Different methods were used. The commonest was the position of
the sun and phases of the moon. Sometimes inventions were also used such as the hourglass. This instrument
consisted of two rounded glass bulbs that were separated by a narrow neck. It contained particles of sand within
it. When turned upside down, a measured amount of sand would drop from the top of the glass to the bottom in
a specific period of time.
In the 17th century, a pendulum clock was invented using the pendulum law discovered by Galileo Galilei. A
pendulum is an object hanging from a fixed point that swings back and forth. According to the pendulum law,
it takes the same amount of time to make one complete sing; that is, swing back and forth.

Specific outcomes
This unit introduces the simple pendulum. It covers the terminologies used to describe the pendulum and
calculations. By the end of this unit, you will be able to:
❖ State the SI unit of time
❖ State the instruments used to measure time
❖ Simple pendulum:
• Label the parts of the simple pendulum
• Define oscillation
• Define period, and work out period calculations
• Define frequency, and work out frequency calculations
• State factors that affect the period of the pendulum


18

Time


TIME
4.1

TIME
• SI unit of time: second (s).
• Other units: minute, hour, day, month, year, century.
• Instruments used to measure time:
• Stopwatch
• Clock
• Pendulum

4.2

SIMPLE PENDULUM
• It consists of a bob attached by a string hanging from a supporter.
• The length of the pendulum (l) is measured from the supporter
to the middle of a bob.
1. OSCILLATION
• Oscillation of the pendulum is the swing of a bob back and forth.
• One complete oscillation of a simple pendulum is the
swing of a bob forth and back to its starting point.
For example, a swing from point A through B to
point C and back to point A is one complete oscillation.
2. PERIOD (T)

• Period is the time taken by a pendulum to complete one oscillation.
• The formula for calculating the period of the pendulum.

T=

t
n

where
T = Period (in seconds)
t = time taken for n oscillations
n = number of oscillations

3. FREQUENCY (f )
• Frequency is the number of oscillations completed in one second.
• SI unit: Hertz (Hz).
• The formula for calculating the frequency of the pendulum.

f =

1
T

where
f = frequency (in Hz)
T = Period (in seconds)

4. FACTORS THAT AFFECT PERIOD OF PENDULUM
i. Length of the pendulum. The length of the pendulum is directly proportional to the period. The
longer the length the higher the period.

ii. Acceleration due to gravity. Gravity is inversely proportional to the period. Therefore, greater
gravity decreases the period of the pendulum.
➢ Note: Mass of bob does not affect the period of a pendulum.

Time

19


REVIEW QUESTIONS
1. The measure of the number of oscillations per second is called
A. Period
B. Amplitude
C. Frequency
D. Vibration
2. A motion of a pendulum repeated over and over again is called
A. Frequency
B. Time
C. Oscillation
D. Period
3. The amount of time required for one oscillation is called
A. Frequency
B. Period
C. Hertz
D. Amplitude
4. If the same pendulum is performed on earth and the moon, its period on the moon will
A. Increase
B. Decrease
C. Stay the same
D. Swing forever

5. If the mass of a bob of a pendulum is increased, the period will
A. Increase
B. Decrease
C. Stay the same
D. Become zero
6. If the length of the pendulum increases, the period will
A. Increase
B. Decreases
C. Stay the same
D. Swing forever
7. A pendulum makes one complete swing in 1.8 seconds. What is its frequency
A. 0.56 Hz
B. 0.59 Hz
C. 1.8 Hz
D. 2.3 Hz
8. A pendulum swings back and forth 5 times in 4 seconds. What is its period?
A. 0.50 seconds
B. 0.80 seconds
C. 1.25 seconds
D. 1.35 second

20

Time


9. The diagram shows a pendulum oscillating.

A. It takes 1.5s to move from A to C and back to B. What is the period of the pendulum?
B. What is its frequency?

C. How long does it take for 5 times complete oscillation?

Time

21