2018_SCIENCE Teacher

Unit 8 - The Simple Electric Circuit

9 10 Activity 8.7 Classifying objects as conductors and
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7 non-conductors (insulators) of electicity
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Observe a piece of wire. Label the metal and plastic part.

It has a metal part that allows electricity to pass through.
The metal part is called a conductor of electricity.

electrical wire It has plastic or rubber part that does not allow electricity to flow.
Plastic or rubber is called a non-conductor of electricity.

A non-conductor is also called an insulator.

Question crocodile clips

Are all objects electrical conductors?
Let us find out.

What you need

a piece of thread, a dry lollipop stick, a metal coin, a piece of glass,
a rubber band, a nail, a plastic ruler and a metal ruler, crocodile clips
Note: Make sure that the objects are dry and not rusty.

What you do

1. Connect the circuit as shown below in Figure 8.10

A piece of thread

Figure 8.10: Connecting a switch to a circuit 141

Unit 8 - The Simple Electric Circuit

2. At the start, do not connect anything between the crocodile clips.
3. Press the switch on.
4. Write down what you observe.

__________________________________________________________________________

Explain your observation.

__________________________________________________________________________

5. Now put the thread between the two crocodile clips.

Questions

Does the bulb light up?_____________

Is electricity flowing?______________

Is the circuit closed or open?____________

What do you conclude?
____________________________________________________________________

6. Remove the thread and do the same experiment with the other objects, each one at a time.
7. Fill in the table below by ticking the right column as you carry out the experiment.

Name of object Bulb lights up Bulb does not light up
Thread
Lollipop stick
Coin
Glass
Rubber band
Nail
Plastic ruler
Metal ruler
Stainless steel spoon
Hairpin
An insulated paper clip

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Unit 8 - The Simple Electric Circuit

From the table, name the objects that allow the bulb to light up.

__________________________________________________________________________

These objects allow electrical energy to pass through them. They are called electrical
conductors.

What are the electrical conductors made of?

______________________________________________________________________

From the table, name the objects that do not allow the bulb to light up.
________________________________________________________________________

These objects do not allow electrical energy to pass through them. They are made of plastic,
rubber or glass. They are called non-conductors or insulators.

I conclude from my observations

Metals are good electrical conductors. They allow electricity to pass through them.
All metals conduct electricity.
Insulators are non electrical conductors.They do not allow electricity to pass through
them.

Electric wires bring electricity to our school and home.
These wires are wrapped up with rubber or plastic as shown in Figure 8.11.
Discuss why.
__________________________________________________________________________

metal (a conductor)

rubber or plastic (an insulator) 143

Figure 8.11: An electrical wire
Plastic and rubber are insulators.
They prevent us from getting an electric shock.
Electric shocks can cause severe burns or death.

Unit 8 - The Simple Electric Circuit
Why is it that we do not get any electric shock when working with our simple electric circuit?
__________________________________________________________________________

Electricity carries electrical energy in wires in a closed circuit.
Can you imagine what may happen if there is a power cut?

Safe use of electricity

Some safety measures must be taken when using electrical appliances:
Do not try to repair broken electric
wires or appliances.
Ask an electrician to do it.

Do not touch an electrical switch or
appliance with wet hands.

electrical switch

Never touch broken electrical wires
lying on the ground (for example, after
a cyclone).

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Unit 8 - The Simple Electric Circuit

You must not connect many power plugs
to one socket.

a power plug Many appliances are connected to one socket.

Do not put metal objects in electrical
sockets.

The important role of electricity in our daily life.

What I have learnt

Electricity has an important role in our daily life.
Electricity can be very dangerous.
We must take necessary precautions so that we do not get electric shocks.

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Unit 8 - The Simple Electric Circuit

Teacher’s note pg 149-155

Answers to end of unit exercises
Exercise 1
Answers to multiple choice questions.
1. B 2. C 3. A 4. D 5. D
Exercise 2
(i) Pupils to label the metal part and plastic cover.
(ii) Function of the plastic cover: To protect us from getting electric shock. (Plastic is a non-

conductor of electricity)
(iii) The metal may be aluminium or copper.
Exercise 3
Pupils match pictures with appropriate words. (Bulb, switch, cell, wire)
Exercise 4
Make sure that all pupils insert + in the top box and – in the bottom box.
Exercise 5
(a) chemical, light.
(b) Switch.
(c) Open.
(d) Complete/closed.
(e) Cell, battery.
(f) Gap.
Exercise 6
(i) Conductors of electricity: nail, metallic sharpener,hair pin.
(ii) Insulator made of: plastic/rubber.
Exercise 7
(i) The circuit is open or not complete. Electricity is not flowing along the wire.
(ii) To complete the diagram, pupils draw a wire from the + end of the cell and connect it to the

other part of the bulb.
(iii) Now the bulb lights up.
(iv) Because the circuit is complete/closed. Electricity is flowing along the wires.

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Unit 8 - The Simple Electric Circuit

Teacher’s note pg 149-155

Exercise 8

(i) This is a test to find out whether the pupil can draw a complete circuit so as to make the fan
work. Refer to Activity 8.6

(ii) Transformation of energy. Chemical energy in the cell transformed to electrical energy in the
wire, which is transformed into movement energy in the fan.

Exercise 9

(i) Pupils have to correctly label the switch, cell and bulb. The wire is already labelled.
(ii) Part that is not connected properly: at parts A of the bulb.
(iii) To rearrange the circuit I tell her to:

press the switch off.
remove one end of either wire X or wire Y from part A of the bulb and connect it to part B of
the bulb.
press the switch on. The bulb lights up.

Exercise 10

(a) Electric oven, computer, electric iron.
(b) Bad practice: Several appliances connected to one socket. Risk of fire, risk of damage to

the appliances.
(c) Advice: one socket to be used for one appliance.
(d) If we handle/touch a live wire, we get an electric shock, we may get burnt.
Precaution in the kitchen.
(e) In the kitchen we must not handle an electrical appliance with wet hands.

Exercise 11

Matching exercise

Cell is a source of electricity

Electric wire conducts electricity

Bulb gives out light

Switch allows or stops the flow of electricity in a circuit

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Unit 8 - The Simple Electric Circuit

Teacher’s note pg 149-155

Exercise 12
(i) No, the bulb will not light up.

Because the circuit is open/not complete/not closed.
(ii) Connect the wire to the +ve end of the cell.
(iii) Use a metallic object to close the gap between the wire and the +ve end of the cell.
Exercise 13
1. True
2. False
3. False
4. True
5. True
6. True
7. False
8. False

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Unit 8 - The Simple Electric Circuit

End of Unit Exercises

Exercise 1

For each item, there is ONE correct answer. Circle the correct answer.

1. A _______________is used either to open or close a circuit.

A cell B switch C bulb D wire

2. Which form of energy flows in an electric circuit?

A heat B sound C electric D movement

3. A material that allows electricity to pass through it is a .......................

A conductor B insulator C plastic cover D non-conductor

4. All .............................. are good electrical conductors.

A glass containers B cotton strings C plastic containers D metals

5. An example of an insulator is ......................... .

A aluminium foil B copper wire C steel spoon D glass

Exercise 2

The diagram shows an electrical wire. Answer the following questions:

(i) Identify and label the (a) metal part and (b) plastic cover.
(ii) What is the function of the plastic cover?
______________________________________________________________________
(iii) Name one metal that is used to make electrical wires. ________________________

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Unit 8 - The Simple Electric Circuit

Exercise 3

Match each picture to its correct name.

cell

bulb

wire

switch

Exercise 4

The picture shows a cell. Write + or – in the correct box.

Exercise 5

Fill in the blanks with an appropriate word from the list given. open
battery gap switch light complete cell chemical

a. The _________________energy in the cell changes to _____________ and heat
energy in the bulb.

b. The _______________ can allow or prevent electricity to flow in the circuit.
c. Electricity does not flow in an ________________ circuit.

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Unit 8 - The Simple Electric Circuit

d. The bulb in the circuit lights up when the circuit is ____________________.
e. The source of electrical energy in the circuit is the __________ or the ____________.
f. A closed or complete circuit does not have a __________ in it.

Exercise 6

Study the list of objects below and answer the questions that follow:
a nail an eraser a metallic sharpener a plastic ruler a hair pin
(i) Which of these are conductors of electricity? ___________________________________
(ii) What is an insulator made of? _________________________________________

Exercise 7

Study the diagram and answer the questions below:

The diagram shows a circuit. The bulb in the circuit
does not light up.
(i) Explain why.
_______________________________________________________________________
(ii) Complete the diagram to close the circuit.
(iii) What can you say about the bulb now?
_______________________________________________________________________

(iv) Explain your answer.
______________________________________________________________________

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Unit 8 - The Simple Electric Circuit Two connecting wires

Exercise 8

A pupil wants to test whether a toy fan given to him works.
He makes a list of the things he needs:
a cell, pieces of wire, a switch and the small fan.
He sets up a circuit to test whether the fan works well.
Draw the circuit in the box provided.

Describe the transformation of energy taking place in the circuit.
__________________________________________________________________________
__________________________________________________________________________

Exercise 9

A pupil sets up an electric circuit as shown in the diagram.
(i) Label the diagram with the following words: switch, cell, bulb, wire.

wire X

Part B

Part A wire Y

wire Z

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Unit 8 - The Simple Electric Circuit

When the pupil presses the switch on, the bulb does NOT light up.
She made a mistake when setting up the circuit.
(ii) Circle that part of the circuit that is not connected properly.
(iii) You want to help her arrange the circuit correctly. What do you tell her?
__________________________________________________________________________
__________________________________________________________________________

Exercise 10

Study the picture which shows a
family using different electrical
appliances. Answer the questions
that follow:

(a) Name two of them.

(i) __________________________

(ii) __________________________

(b) Describe one bad practice of using electricity that you see.

____________________________________________________________________


(c) What advice can you give to this family.

____________________________________________________________________

(d) Electrical energy can be very dangerous. Explain how.

____________________________________________________________________

(e) Give another precaution that must be taken in the kitchen when using electricity.

_____________________________________________________________________

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Unit 8 - The Simple Electric Circuit

Exercise 11

Draw lines from column A to column B to show the correct function of each object in
column A.

Part A Part B

cell conducts electricity

electric wire gives out light

bulb allows or stops the flow

of electricity in a circuit

switch is a source of electricity

Exercise 12

Study the circuit and answer the questions below:

(i) Will the bulb light up?_______________

Explain your answer.

_______________________________________________________________


(ii) Draw a line to complete the circuit.

(iii) List two things you can do to close the gap.

1.________________________________________________________________

2.________________________________________________________________

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Unit 8 - The Simple Electric Circuit

Exercise 13

In the table below, several statements are given. Write True or False in the table.

Statement True/False
1 Copper is a good conductor of electricity.

2 A bulb is used to open and close a circuit.

3 Electrical energy can flow only in an open circuit.

4 We must not touch electrical appliances with wet hands.

5 In an electric bell, electrical energy is changed into sound
energy.

6 We should switch off the TV when nobody is watching.

7 It is NOT important to save energy.

8 We should connect many appliances in the same socket.

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Unit 8 - The Simple Electric Circuit

At the end of this unit, I can

• recognise the bulb, the cell, the switch, the wire in a circuit.
• construct an electric circuit with an electric wire, a bulb and a cell.
• state the importance of electrical conductors.
• state the importance of insulators.
• show the transformation of energy through experiments.
• protect myself from electric shocks.

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© Mauritius Institute of Education 2018