Hands-on Science Textbook Primary 5 Chapter 05

Chapter

5

Electricity

Light bulbs brighten up dark areas. They need electricity to
work. The bulb in a flashlight needs electricity to light up. How
does the bulb get electricity?

What do I know about electricity?

1.
2.
3.

What do I want to know about electricity?
1. Describe a simple electric circuit, its components and their functions.
2. Recognize the difference between open and closed circuits, and the symbols

used to represent the electrical circuit components in a diagram.
3. Explain the difference between series and parallel circuits.
4. Identify the factors that affect the brightness of bulbs in a circuit.
5. Identify electrical conductors and insulators, and their uses in our daily life.

5.1 Electric Circuits

Batteries supply electricity for a torch to work. When electricity flows through the bulb,
it lights up. The path along which the electricity flows is called the electric circuit.

Switch Bulb
Wire Battery

A simple electric circuit is made up of a battery, a connecting wire, a switch and a bulb.
These are the components of the circuit. A torch is made up of these parts. When these
parts are connected, electricity flows through the circuit and the torch lights up. The flow of
electricity is called electric current.

Electricity that moves from one place to another is called electric current.
Electricity that gathers in one place is known as static electricity. This
explains why a balloon sticks to us after we rub it against our clothes.

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Parts of an Electric Circuit

The basic parts of an electric circuit are shown as below.

Battery Positive
terminal
• It is a source of electricity.
Negative • It has two terminals.
terminal • At the positive terminal, there is

a ‘+’ symbol.
• At the negative terminal, there is

a ‘–’ symbol.

Bulb

Tungsten • There is a tungsten filament in
filament the bulb.

Glass • When electricity passes through
bulb it, it gives out light.

Connecting wire • It is made of copper wires
Switch covered with a layer of plastic or
rubber.

• It connects the parts of the
circuit together.

• It allows electricity to flow
through it.

• It is used to break or complete
an electric circuit.

• If the switch is turned on, the
electric current flows.

• If the switch is turned off, the
electric current stops flowing.

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5.2 Open and Closed Circuits

A switch is used to open or close a circuit. The circuit allows electric current to flow through it.

A closed circuit An open circuit

• When the switch is on/ closed, • When the switch is off / open, the
the bulb lights up. bulb will not light up.

• Electric current flows through the • This is because no electric current
circuit to light up the bulb. flows through the circuit.

• The circuit is said to be a • The circuit is said to be an
complete circuit or a closed incomplete circuit or an open
circuit. circuit.

• In a closed circuit, all of the • In an open circuit, not all of the
parts are properly connected. parts are properly connected.

Let’s Try! How do we make an electric circuit that lights up
a bulb?

Things needed: • Battery
• Bulb
• Connecting wire

1. You are given a battery, a bulb and a connecting wire.
2. Join them together based on the diagrams given.

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A BC

DE F
3. Which circuits light up the bulb? Why?

4. What is your conclusion from this activity?

Circuit Diagrams and Symbols

A circuit diagram represents an actual circuit. It is a drawing that uses simple symbols to
represent the different components in a circuit.

Component

Battery Connecting wire Bulb Switch
Open switch
Symbol Closed switch

Chapter 5 Electricity 69

Circuit diagrams show us how the components of an electric circuit are connected.

Switch

Bulb

A closed circuit Battery

A closed circuit diagram

Switch

Bulb

An open circuit Battery

An open circuit diagram

Let’s Try! How do we build simple circuits based on circuit
diagrams?

• Batteries • Bulb holder

Things needed: • Battery holder • Switch

• Bulbs • Connecting wires with crocodile clips

1. You are given the things needed to build simple circuits.
2. Build simple circuits based on the circuit diagrams shown below.

AB CD
70 Hands-on Science Primary 5

3. Record your observations in the table below.

Circuit Does the bulb What is the corrective action to light up the bulb?
light up?

A

B

C

D

4. Why does the bulb light up when it is connected correctly to the battery?

5. What is your conclusion from this activity?

5.3 Series and Parallel Circuits

Electric current flows through a closed circuit to light up a bulb. Bulbs can be arranged
differently to build a series circuit or a parallel circuit.

Series Circuits

A series circuit is a closed circuit in which all the components are connected in a row, one
after another to form a closed loop. The electric current flows in one path. Can you identify
the currecnt flow path in circuit A, B and C?

Circuit A is made up of one
bulb and one battery.

Circuit A Circuit B is made up of two
Circuit B bulbs, a closed switch and
one battery.

Chapter 5 Electricity 71

Circuit C is made up of two
bulbs and three batteries.

Circuit C

Parallel Circuits

A parallel circuit is a closed circuit in which the current flows into two or more paths. Can you
indentify the current flow paths in circuits D, E and F?

Circuit D is made up
of two bulbs and two
batteries. Electric current
flows in two paths.

Circuit D

Circuit E is made up
of two bulbs, a closed
switch and one battery.
Electric current flows in
two paths.

Circuit E

Circuit F is made up of
three bulbs and two
batteries. Electric current
flows in three paths.

Circuit F
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Factors Affecting the Brightness of a Bulb

The brightness of a bulb in a circuit depends on the amount of electric current flowing through
it. We can adjust the brightness of the bulb by making the following changes:
• The number of batteries used
• The number of bulbs used
• The arrangement of bulbs

Let’s Try! Will the brightness of the bulb be affected by the
number of bacteria used in a circuit?

• Batteries • Bulb holder

Things needed: • Battery holder • Switch

• Bulbs • Connecting wires with crocodile clips

1. Connect a battery to a bulb as shown in the circuit below. Switch on the circuit and
observe the brightness of the bulb. Record your observation.

2. Switch off the circuit. Connect another battery to the existing battery side by side.
Switch on the circuit again and record the brightness of the bulb.

3. Repeat step 2 by adding one more battery to the circuit. Record your observation.
4. Complete the table below to record the brightness of the bulbs.

Circuit Brightness of the bulbs
Circuit with one battery
Circuit with two batteries
Circuit with three batteries
5. How do we make the bulb brighter?

6. If we reduce the number of batteries, what happens to the brightness of the bulb?

7. What is your conclusion from this activity (Part A)?

Chapter 5 Electricity 73

Let’s Try! Will the brightness of the bulb be affected by the
number of bulbs used in a circuit?

1. Connect a battery to a bulb and a switch to form a simple circuit. Switch on the circuit
and observe the brightness of the bulb. Record your observation.

2. Switch off the circuit. Connect another bulb to the circuit as shown below. Switch on the
circuit again and record the brightness of the bulbs.

3. Repeat step 2 by adding one more bulb to the circuit. Record your observation.
4. Complete the table below to record the brightness of the bulb.

Circuit Brightness of the bulb

Circuit with one bulb
Circuit with two bulbs

Circuit with three bulbs

5. Draw the circuit diagrams for each of the circuits built.

Circuit with one bulb Circuit with two bulbs Circuit with three bulbs

6. How do we make the bulb dimmer?

7. If we reduce the number of bulbs, what happens to the brightness of the other bulbs?

8. What variable is kept the same in this activity?

9. What variable is changed in this activity?

10. What variable is responding in this activity?

11. What is your conclusion from this activity?

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Let’s Try! Will the brightness of the bulb be affected by the
arrangement of bulbs in a circuit?

1. Build two circuits as shown below.

Circuit A Circuit B

2. Switch on the circuits and observe the brightness of the bulbs of each circuit.
3. Compare the brightness of the bulbs and record your observations in the table below.

Circuit Brightness of the bulbs
A
B

4. Draw the circuit diagrams for both circuits.

Circuit A Circuit B
5. Which circuit has brighter bulbs? Why?

6. How should the bulbs be arranged in a circuit to give the brightest light?

7. Remove a bulb circuit A. What happens to the other bulb? Why?

8. Remove a bulb from circuit B. What happens to the other bulb? Why?

9. What is your conclusion from this activity?

Chapter 5 Electricity 75

A bulb in a circuit lights up brighter when more electricity flows through it. This can be done
by adding more batteries to the circuit.

BATTERY AA BATTERY AA BATTERY AA

The bulb lights up brightly. The bulb becomes brighter.

How do you make a bulb dimmer? A bulb in a circuit becomes dimmer if more bulbs are
added to the circuit.

BATTERY AA BATTERY AA

The bulb lights up brightly. The bulbs are dimmer.

There are two ways in which components of an electric circuit can be arranged. In a series
circuit, there is only one path for the electricity to flow through the bulbs. If more bulbs are
added, the brightness of the bulbs will decrease. If one bulb is removed or spoilt, the other
bulbs do not light up because the circuit is incomplete.

A series circuit A series circuit diagram

In a parallel circuit, there are separate paths for electricity to flow through the bulbs. The
electric current divides and flows through each of the three bulbs separately. If one bulb is
removed or spoilt, the other bulbs will still light up.

A parallel circuit A parallel circuit diagram
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Let’s Think A
B
Analyze the circuit diagram.
What happens to the other bulbs if C
(a) bulb A is removed?
(b) bulb B is removed?
(c) bulb C is removed?

Let’s Find Out!

Find out the advantages and disadvantages of:
• the series circuit
• the parallel circuit
Make the comparison in a table. Share your findings with your friends.

5.4 Electrical Conductors and Insulators

Materials that allow electricity to flow through them are electrical conductors, for examples,
metal keys, magnets, bolts and nuts. They can conduct electricity.
Materials that do not allow electricity to flow through them are electrical insulators. Glass,
plastic and cloth are examples of electrical insulators. They cannot conduct electricity. When
they are connected to a circuit, the bulb does not light up.

Copper wires

Electrical wires are made of copper that is
a good conductor of electricity.

Plastic or rubber insulators

Plastic and rubber are insulators. They do
not allow electricity to flow through them.
A plastic or rubber covering is wrapped
around electrical wires to protect us from
electric shocks.

Chapter 5 Electricity 77

Water
Water is a conductor. Watery substances
such as orange juice and tomato juice can
conduct electricity even though they are
vegetables or fruits.

Glass
Glass is a good insulator because
it does not allow electricity to flow
through it.

Rubber
Rubber is a more commonly used insulator.
Weave encouraged to wear rubber gloves
and boots while working with electrical
connections.

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Let’s Try! What material can conduct electricity?

• Battery holder • Steel nail • Straw

• Batteries • Wooden ruler • Magnet

Things needed: • Connecting wires • Coin • Handkerchief

with crocodile clips • Paper clip • Eraser

• Bulb • Glass rod

1. Set up the apparatus as shown. Batteries Bulb
2. Connect a steel nail to the crocodile clips. Write
down the material used to make the steel nail. Crocodile
3. Observe whether the bulb lights up when it is clip Test object
connected to the steel nail.
4. Record your observation in the table below.

Object Material used to make Does the bulb light up?
the object
Steel nail
Coin
Eraser
Glass rod
Wooden ruler
Paper clip
Straw

Magnet

Handkerchief

5. Repeat steps 2 and 3 with other objects listed in the table. Then, record your observations.
6. What can you infer if the bulb lights up?

7. Group the materials into electrical conductors and electrical insulators.

Electrical conductor Electrical insulator

8. What is your conclusion from this activity?

Chapter 5 Electricity 79

Ways to Use Electricity Safely

You have learned how to conserve electricity in Primary 1, can you recall what are the ways?
Other than using electricity wisely, we must make sure that we use it safely.

Do not touch electrical
parts with wet hands.
This is because water
is a conductor that
allows electricity to
flow through it.

Switch off electrical appliances after
use. Do not leave them on ‘standby’
mode. This is a way to conserve
electricity.

Do not connect too many plugs Hold the plastic handle when using
to a socket to reduce the risk of electrical appliances. Plastic is an
overloading and fire. electrical insulator that protects us
from direct contact with electricity.

Do not touch or use exposed electrical
wires that may cause electric shocks.

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Fill in the blanks.

closed   series   parallel   switch  
   insulator   batteries   circuit   conductor  

bulbs   open   safely   symbols  

1. An electric is the path through electricity flows.

2. The components of an electric circuit are the battery, , bulb and
connecting wire.

3. A circuit is a circuit through which electricity can flow through the
components.

4. A bulb in an circuit does not light up.

5. A circuit diagram is a drawing that uses to represent the components
in an actual circuit.

6. In a circuit, there is only one path for the electricity to flow.

7. In a circuit, there is more than one path for the electricity to flow.

8. A bulb will light up brighter if more are added to the circuit.

9. A bulb will light up dimmer if more are added to the circuit.

10. An electrical allows electricity to flow through it.

11. An electrical does not allow electricity to flow through it.

12. We must conserve electricity and use it .

Let’s Scan

Chapter 5 Electricity 81

Map It Out

Electricity

Electric Open and Series and Electrical conductor
circuit closed circuit parallel circuit and insulator

Components: • Open circuit: • Series circuit: • Electrical
• Bulb electric electric current flows conductor:
• Battery
• Switch current in one path allows
• Connecting cannot flow • Parallel circuit: electricity to
wire through it electric current flow through it
• Closed
circuit: divides into two or • Electrical
electric more paths insulator:
current can • Factors affecting the
flow through brightness of a bulb: does not
it and light - the number of allow
up the bulb electricity to
batteries used flow through it
- the number of

bulbs used
- the arrangement

of the bulbs

Explain It Online

QuickQuiz

Circuit diagram
Drawing that represents an actual electric circuit

Electrical conductor

Material that allows electric current to pass through it to conduct
electricity

Electrical insulator Material that does not allow electric current to pass through it to
conduct electricity

Parallel circuit
A closed circuit in which the current divides into two or more paths

Series circuit
A closed circuit in which the electric current flows in one path

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