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Science questions, unit 5
Nama / NameKelas / ClassTarikh / Date

Electricity

43 marks. Use Practice to check each answer as you go, or Exam to answer everything first. Ask a grown-up to help you mark the written answers.

Section A: objective questions

10 marks
Choose the best answer for each question.
1

Question 1

Which source of electrical energy changes chemical energy into electrical energy and is used to start up a car?
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D
An accumulator converts chemical energy into electrical energy and starts vehicles such as cars. A dry cell also changes chemical energy, but it is used for small things such as toy cars.
For the teacher: Remembering, low difficulty, standard 5.1.1
Textbook p. 117
2

Question 2

A calculator is powered by a solar cell. What kind of energy does the solar cell change into electrical energy?
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A
Solar cells change light energy from the Sun into electrical energy.
For the teacher: Remembering, low difficulty, standard 5.1.1
Textbook p. 116
3

Question 3

Diagram 1 shows the circuit diagram of three bulbs, P, Q and R. What type of circuit is this?
Circuit diagram: one dry cell, a closed switch and three bulbs P, Q and R in one loop
Diagram 1
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B
All three bulbs are in one chain with only one path for the electric current. That is a series circuit.
For the teacher: Understanding, low difficulty, standard 5.2.1
Textbook p. 118
4

Question 4

How many paths does the electric current have in the circuit in Diagram 2?
Circuit diagram: one dry cell with three branches, each with a closed switch and a bulb
Diagram 2
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C
Each branch is one path. The circuit has three branches, so there are three paths.
For the teacher: Understanding, low difficulty, standard 5.2.1
Textbook p. 119
5

Question 5

Which symbol represents an open switch?
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B
An open switch is drawn with a gap and a slanted line. A closed switch is a straight line between two dots (P). R is a bulb and S is two dry cells.
For the teacher: Remembering, low difficulty, standard 5.2.2
Textbook p. 120
6

Question 6

Diagram 3 shows circuit P and circuit Q. Each has one dry cell and two identical bulbs. Which statement is correct?
Circuit P: one dry cell, a switch and bulbs A and B in a series circuit
Circuit P
Circuit Q: one dry cell with two branches, bulbs C and D
Circuit Q
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A
Circuit Q is a parallel circuit. Each branch gets the same electrical energy, so its bulbs are brighter. In series circuit P the two bulbs share the current and are dimmer.
For the teacher: Applying, medium difficulty, standard 5.2.3
Textbook p. 123
7

Question 7

Diagram 4 shows a series circuit. Which change will make bulbs A and B brighter?
Circuit diagram: one dry cell, a closed switch and bulbs A and B in a series circuit
Diagram 4
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C
In a series circuit, more dry cells give brighter bulbs. Another bulb would make every bulb dimmer.
For the teacher: Applying, medium difficulty, standard 5.2.4
Textbook p. 125
8

Question 8

Diagram 5 shows a parallel circuit. Switch X is open and switch Y is closed. Which bulb lights up?
Parallel circuit: bulb A on a branch with open switch X, bulb B on a branch with closed switch Y
Diagram 5
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B
Bulb A's branch is incomplete because switch X is open. The branch of bulb B is complete, so bulb B still lights up.
For the teacher: Analysing, medium difficulty, standard 5.2.6
Textbook p. 130
9

Question 9

Which action helps a family to save electrical energy?
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C
An LED lamp uses less electrical energy than a filament lamp. The other three actions waste electrical energy.
For the teacher: Applying, low difficulty, standard 5.3.1
Textbook p. 133
10

Question 10

Which is a safe way to use electrical appliances?
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D
Turn off the switch before pulling out the plug. The other actions can cause a short circuit or electrocution.
For the teacher: Understanding, low difficulty, standard 5.3.3
Textbook p. 138

Section B: structured questions

33 marks
Answer all questions. Circle the answer or write it in the space.
11

Question 11

Choose the correct answer for each source of electrical energy.
[1 mark] (a)A dynamo changes ______ energy into electrical energy.
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kinetic
When the wheel turns, the dynamo turns too, and kinetic energy is changed into electrical energy.
[1 mark] (b)A generator changes the chemical energy of ______ into electrical energy.
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fossil fuels
[1 mark] (c)Which source is used in satellites and calculators?
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Solar cell
For the teacher: Remembering, low difficulty, standard 5.1.1
Textbook p. 117
12

Question 12

Diagram 6 shows two circuits, R and S, each with two bulbs.
Circuit R: one dry cell, a switch and two bulbs in one loop
Circuit R
Circuit S: one dry cell with two branches, each with a switch and a bulb
Circuit S
[1 mark] (a)Circuit R is a ______ circuit.
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series
[1 mark] (b)Circuit S is a ______ circuit.
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parallel
[1 mark] (c)Which circuit has more than one path for the electric current?
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S
Each branch of a parallel circuit is a path.
For the teacher: Understanding, low difficulty, standard 5.2.1
Textbook p. 119
13

Question 13

Diagram 7 shows a circuit drawn with symbols.
Circuit diagram: two dry cells, an open switch S and one bulb in one loop
Diagram 7
[1 mark] (a)How many dry cells are in the circuit?
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Tick each point you got.
[2 marks] (b)Is the bulb lit? Give a reason for your answer.
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Tick each point you got.
For the teacher: Applying, low difficulty, standard 5.2.2
Textbook p. 120
14

Question 14

Mei Ling builds circuits A and B in Diagram 8. Each has one dry cell and three identical bulbs, and all the switches are closed.
Circuit A: one dry cell, a switch and three bulbs in one loop
Circuit A
Circuit B: one dry cell with three branches, each with a switch and a bulb
Circuit B
[1 mark] (a)In which circuit are the bulbs brighter?
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Circuit B
[2 marks] (b)Explain your answer.
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Tick each point you got.
For the teacher: Analysing, medium difficulty, standard 5.2.3
Textbook p. 124
15

Question 15

Aiman builds series circuits with one bulb and a different number of dry cells. He observes the brightness of the bulb. The table shows his results.
Number of dry cellsBrightness of the bulb
1bright
2brighter
3brightest
[1 mark] (a)State the manipulated variable.
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Tick each point you got.
[1 mark] (b)State the responding variable.
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Tick each point you got.
[2 marks] (c)Write a conclusion for this investigation.
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Tick each point you got.
For the teacher: Analysing, low difficulty, standard 5.2.4
Textbook p. 125
16

Question 16

Diagram 9 shows three parallel circuits with one, two and three bulbs. Each uses one dry cell.
Three parallel circuits A, B and C with one, two and three bulbs; all bulbs are equally bright
Diagram 9
[1 mark] (a)How does the brightness of one bulb in circuit A compare with one bulb in circuit C?
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The same
Every bulb has its own branch, so adding bulbs does not change the brightness.
[1 mark] (b)Suggest how to make the bulbs in circuit C brighter.
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Tick each point you got.
[1 mark] (c)If the same three bulbs were joined in a series circuit with one dry cell, would they be brighter, dimmer or the same as in circuit C?
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Dimmer
In a series circuit the bulbs share the electric current, so they are dimmer.
For the teacher: Applying, medium difficulty, standard 5.2.5
Textbook p. 128
17

Question 17

Diagram 10 shows a parallel circuit and Diagram 11 shows a series circuit.
Parallel circuit with three branches: S1 closed with bulb A, S2 open with bulb B, S3 closed with bulb C
Diagram 10
Series circuit with switch X open, switch Y closed and bulbs P and Q
Diagram 11
[2 marks] (a)In Diagram 10, which bulbs light up?
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Tick each point you got.
[1 mark] (b)Give a reason why bulb B does not light up.
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Tick each point you got.
[1 mark] (c)In Diagram 11, what is the condition of bulbs P and Q?
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Tick each point you got.
For the teacher: Analysing, high difficulty, standard 5.2.6
Textbook p. 131
18

Question 18

Ana's family has several lamps at home. One day one bulb in the living room stops working, but all the other lamps still light up.
[1 mark] (a)Are the lamps connected in a series circuit or a parallel circuit?
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Parallel circuit
[2 marks] (b)Explain why the other lamps still light up.
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Tick each point you got.
For the teacher: Evaluating, medium difficulty, standard 5.2.1
Textbook p. 119
19

Question 19

Diagram 12 shows three types of lamps. Ahmad's family wants to lower its monthly electricity bill.
LED lamp and compact fluorescent lamp with ticks, filament lamp with a cross
Diagram 12
[1 mark] (a)Which lamp should Ahmad's family stop using?
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Filament lamp
A filament lamp uses more electrical energy. LED and compact fluorescent lamps are energy-saving.
[2 marks] (b)Suggest two other ways the family can save electrical energy.
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Any 2 points
Tick each point you got.
For the teacher: Creating, low difficulty, standard 5.3.1
Textbook p. 133
20

Question 20

Diagram 13 shows a phone that has been charging for a very long time.
A smartphone connected to a charging cable with smoke around it
Diagram 13
[1 mark] (a)What could happen if a phone is charged for too long?
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Tick each point you got.
[1 mark] (b)How can this mishandling be avoided?
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Tick each point you got.
[2 marks] (c)State two safety precautions when handling electrical appliances.
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Any 2 points
Tick each point you got.
For the teacher: Applying, low difficulty, standard 5.3.2
Textbook p. 136