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Primary Science · Year 4Chapter 9 · Electricity and circuits
Year 4 · Chapter 9

Electricity and circuits

By the end of this chapter you will be able to

  • Name common appliances that run from the mains, and those that run from cells
  • Name the basic parts of a simple series circuit: cell, wire, bulb, switch and buzzer
  • Read the symbols for a cell, a bulb, a switch and a buzzer
  • Say whether a lamp will light, using the idea of a complete loop
  • Explain how a gap or an open switch breaks the loop
  • Use safe practice, with cells and a bulb holder, and a grown-up

You should already know

  • Electricity is not taught in Year 3; these are the first ideas of circuits (Year 4 Science)
  • Forces, magnets and the idea of a force acting at a distance (Year 3 Science, Chapter 9)

Where this leads

  • Switches, conductors and insulators, and which materials let electricity flow (Year 4 Science, Chapter 10)
  • Circuits, voltage and symbols in more detail (Year 6 Science)

National Curriculum for England, Key Stage 2 science, Year 4. Content: E1 identify common appliances that run on electricity, E2 construct a simple series circuit, identifying and naming its basic parts, including cells, wires, bulbs, switches and buzzers, E3 identify whether or not a lamp will light in a simple series circuit, based on whether or not the lamp is part of a complete loop with a battery.

Exercise P  Do you remember?

1
FName a metal. Write one metal.
2
FHow many things do you change in a fair test? Write the number.
3
FWhat is the name of the first stage when a seed starts to grow? Write the word.
4
FWhat unit do we use to measure temperature? Write the words.
5
FIs a rock a solid? Write yes or no.
9.1

Appliances that use electricity

Year 4
E1: identify common appliances that run on electricity
Video lesson: Appliances that use electricityComing soon
Story. Ruby’s family has a kettle, a toaster and a television in the kitchen and living room. Her torch and the remote control work differently. “Why do some things plug in, and some do not?” she asks. Mr Patel says, “Some use the mains, and some use cells, which are batteries.”

An appliance is a machine that uses electricity to do a job. Many appliances run from the mains, which is the electricity supply in a wall socket. Others, such as a torch or a remote control, run from cells (batteries).

Important: mains electricity is dangerous. Never touch a plug, a socket or a wire with wet hands, and never push anything into a socket.

The table sorts six appliances by where they get their electricity.

ApplianceHow it gets its electricity
kettlefrom the mains (a wall socket)
toasterfrom the mains (a wall socket)
televisionfrom the mains (a wall socket)
fanfrom the mains (a wall socket)
torchfrom cells (batteries)
remote controlfrom cells (batteries)

Key ideas

  • Appliances such as kettles, toasters, televisions and fans run from the mains.
  • Torches and remote controls run from cells.
  • Mains electricity is dangerous: never touch a socket or a plug with wet hands.
  • In school practicals, use cells and a bulb holder only.
Worked example 9.1.1
Which appliance in the table runs from cells: kettle or torch? Write the name.

Method. Read the table in section 9.1.

  1. Find the two names. The kettle runs from the mains, and the torch runs from cells.
    torch
  2. Name the one from cells. So the torch runs from cells.
    torch
  3. Write the answer.
    torch

Check. A torch uses batteries. ✓

Worked example 9.1.2
How many appliances in the table run from the mains? Write the number.

Method. Count the mains rows.

  1. Read the table. The mains rows are kettle, toaster, television and fan.
    four
  2. Count them. There are four appliances that run from the mains.
    4
  3. Write the answer.
    4

Check. Four plus two is six appliances in the table. ✓

Worked example 9.1.3
Is it safe to put a finger into a wall socket? Write yes or no.

Method. Think about mains electricity.

  1. Think about the socket. A wall socket carries mains electricity, which can cause serious harm.
    serious harm
  2. Decide. So it is never safe to put a finger in a socket.
    no
  3. Write the answer.
    no

Check. Mains electricity must be left to a grown-up. ✓

Watch out

Watch out: an appliance that plugs in is not the same as an appliance that uses cells. Do not assume that every electrical thing can run from a battery.

Try it at home or school (with a grown-up). Walk round your home with a grown-up. Find three appliances that plug into the wall, and two that use batteries. Do not touch any plugs or sockets. Say which ones run from the mains.

Exam tip

Grown-up tip. Ask: “Does this plug in, or does it use batteries? Why should we never touch the plug with wet hands?” Let your child name the appliances and say how each one is powered.

Exercise 9A  Appliances that use electricity

1
FName one appliance from the table in section 9.1 that runs from the mains. Write one name.
2
FWhich appliance in the table runs from cells: torch or kettle? Write the name.
3
FHow many appliances in the table run from the mains? Write the number.
4
FHow many appliances in the table run from cells? Write the number.
5
FHow many appliances are in the table altogether? Write the number.
6
FWhich supply is in a wall socket: mains or cells? Write the word.
7
FIs a torch powered by cells? Write yes or no.
8
FShould you touch a plug or a socket with wet hands? Write yes or no.
9
PSWhich is the safer source of electricity for a school practical: cells or the mains? Write the word.
10
PSA remote control runs from cells. Is this a mains appliance? Write yes or no.
11
PSWorking scientifically. Predict whether a remote control runs from the mains or from cells. Write one prediction with a reason.
12
RExplain why a grown-up must help with any electrical practical at home. Write one sentence.
9.2

The parts of a simple series circuit

Year 4
E2: construct a simple series circuit, identifying and naming its basic parts, including cells, wires, bulbs, switches and buzzers
Video lesson: The parts of a simple series circuitComing soon
Story. Leo builds his first circuit with a cell, two wires, a bulb in a holder and a switch. “What is each part for?” he asks. Ms Chen says, “Let us name them first. Then you can build the circuit with a grown-up, step by step.”

A series circuit is a loop with all its parts in one line, so the electricity goes round the loop, one part after another. The basic parts are the cell, the wires, the bulb (also called a lamp), the switch and the buzzer.

PartWhat it does
cell (battery)pushes the electricity round the circuit
wirecarries the electricity from one part to the next
bulb (lamp)lights up when the electricity flows through it
switchopens or closes the loop, to turn the circuit on or off
buzzermakes a sound when the electricity flows through it
+-cellbulbswitchbuzzer
The symbols for a cell, a bulb, a switch and a buzzer.

Key ideas

  • A series circuit is a single loop, with all its parts in one line.
  • The cell pushes the electricity round the circuit.
  • The wires carry the electricity from one part to the next.
  • The bulb lights, and the buzzer makes a sound, when electricity flows through them.
Worked example 9.2.1
Which part of a circuit pushes the electricity round the loop? Write the name.

Method. Read the table in section 9.2.

  1. Find the part. The cell pushes the electricity round the circuit.
    cell
  2. Name the part. So the part that pushes the electricity is the cell.
    cell
  3. Write the answer.
    cell

Check. A battery is another name for a cell. ✓

Worked example 9.2.2
Which part turns the circuit on or off? Write the name.

Method. Read the table in section 9.2.

  1. Find the part. The switch opens or closes the loop.
    opens or closes
  2. Name the part. So the switch turns the circuit on or off.
    switch
  3. Write the answer.
    switch

Check. Opening the switch breaks the loop. ✓

Worked example 9.2.3
Which part is the same as a lamp? Write the name.

Method. Think about the table.

  1. Read the table. The bulb lights up, and it is also called a lamp.
    lamp
  2. Name the part. So a lamp is another name for the bulb.
    bulb
  3. Write the answer.
    bulb

Check. A bulb and a lamp are the same part. ✓

Watch out

Watch out: a cell is not the same as a bulb. The cell pushes the electricity round, and the bulb uses it to light up.

Try it at home or school (with a grown-up). Look at a torch with a grown-up, and find the cell, the bulb and the switch. Say which part does each job. Do not take the batteries out, and do not touch the bulb while it is hot.

Exam tip

Grown-up tip. Ask: “Which part pushes the electricity? Which part lights up? Which part turns it on?” Let your child name each part in the torch.

Exercise 9B  The parts of a simple series circuit

1
FWhich part of a circuit pushes the electricity round the loop? Write the name.
2
FWhich part carries electricity from one part to the next? Write the word.
3
FWhich part lights up when electricity flows through it? Write the word.
4
FWhich part turns the circuit on or off? Write the word.
5
FWhich part makes a sound when electricity flows through it? Write the word.
6
FHow many basic parts are in the table in section 9.2? Write the number.
7
FWhat is another name for a bulb in a circuit? Write the word.
8
FFill in the gap: a cell is also called a ___. Write the word.
9
PSAli says a circuit needs a switch to work. Is Ali right? Write yes or no.
10
PSLook at the symbols in section 9.2. Which symbol has a long line and a short line? Write the name.
11
PSWorking scientifically. Plan a safe way to build a simple circuit with a cell, a bulb in a holder, and two wires. Write one safety rule.
12
RExplain what a switch does in a circuit. Write one sentence.
9.3

Will the lamp light? The complete loop

Year 4
E3: identify whether or not a lamp will light in a simple series circuit, based on whether or not the lamp is part of a complete loop with a battery
Video lesson: Will the lamp light? The complete loopComing soon
Story. Priya connects a cell, a lamp and two wires. The lamp lights up. “Now I will take one wire off the cell,” she says. “Will it still light?” Mr Patel says, “Think about the loop. Is it complete?”

The electricity can only flow when there is a complete loop, from the cell, through the wires and the lamp, and back to the cell. If the loop has a gap, or a switch is open, the loop is broken, and the lamp does not light.

So a lamp lights only when it is part of a complete loop with the cell.

+-lamp lights
A complete loop: a cell, wires, a switch that is closed, and a lamp. The lamp lights.
switch open+-lamp does not light
The loop is broken by an open switch. The lamp does not light.

The table shows five set-ups, and whether the lamp lights in each one.

Set-upDoes the lamp light?
a cell, wires and a lamp in one complete looplights
a gap in one of the wires, so the loop is brokendoes not light
a switch that is open, so the loop is brokendoes not light
a switch that is closed, so the loop is completelights
a lamp with a wire to only one end of the celldoes not light

Key ideas

  • A lamp lights only when it is part of a complete loop with the cell.
  • A gap in a wire breaks the loop, so the lamp does not light.
  • An open switch breaks the loop, so the lamp does not light.
  • A closed switch completes the loop, so the lamp lights.
Worked example 9.3.1
In a complete loop with a cell, wires and a lamp, does the lamp light? Write the word: lights or does not light.

Method. Check whether the loop is complete.

  1. Check the loop. The loop goes all the way round, from the cell to the lamp and back.
    all the way round
  2. Decide. A complete loop lets the electricity flow, so the lamp lights.
    lights
  3. Write the answer.
    lights

Check. The first row of the table says the lamp lights. ✓

Worked example 9.3.2
A wire has a gap in it. Does the lamp light? Write the words: lights or does not light.

Method. Check the loop.

  1. Check the wire. The gap breaks the loop, so the electricity cannot flow.
    breaks the loop
  2. Decide. Without a complete loop, the lamp does not light.
    does not light
  3. Write the answer.
    does not light

Check. The second row of the table says the same. ✓

Worked example 9.3.3
The switch is closed, and the loop is complete. Does the lamp light? Write the word: lights or does not light.

Method. Check the switch.

  1. Check the switch. A closed switch completes the loop.
    closed
  2. Decide. A complete loop lets the electricity flow, so the lamp lights.
    lights
  3. Write the answer.
    lights

Check. The table says a closed switch lights the lamp. ✓

Watch out

Watch out: a lamp touching one wire is not in a complete loop. The lamp must be joined to the cell by a loop that goes all the way round.

Try it at home or school (with a grown-up). With a grown-up, join a cell, a bulb in a holder and two wires to make a loop. Check that the bulb lights. Then take one wire off, and check again. Do not touch the bulb while it is hot.

Exam tip

Grown-up tip. Ask: “Is the loop complete? What happens when you take one wire off?” Let your child explain the loop in their own words.

Exercise 9C  Will the lamp light? The complete loop

1
FIn a complete loop with a cell, wires and a lamp, does the lamp light? Write yes or no.
2
FIf a wire has a gap in it, does the lamp light? Write yes or no.
3
FDoes the lamp light when the switch is open? Write yes or no.
4
FDoes the lamp light when the switch is closed? Write yes or no.
5
FDoes a lamp light when it has a wire to only one end of the cell? Write yes or no.
6
FHow many of the five set-ups in the table light the lamp? Write the number.
7
FHow many of the five set-ups in the table do not light the lamp? Write the number.
8
FFill in the gap: a lamp lights only when the loop is ___. Write the word.
9
PSRuby says a lamp lights if it touches one wire. Is Ruby right? Write yes or no.
10
PSAli closes the switch, and the lamp lights. Did the loop become complete or broken? Write the word.
11
PSWorking scientifically. Predict whether the lamp will light if the switch is open. Write yes or no, and then test it with a grown-up.
12
RExplain why a lamp does not light when there is a gap in the wire. Write one sentence.
9.4

Drawing and reading a circuit

Year 4
E2: construct a simple series circuit, identifying and naming its basic parts
Video lesson: Drawing and reading a circuitComing soon
Story. Yusuf draws his circuit for the class. “I used the symbols,” he says. “The cell has a long line and a short line, and the bulb is a circle with a cross.” Ms Chen says, “Good. Now anyone can read your drawing and build the circuit.”

Scientists draw circuits with symbols, so that the same drawing can be read anywhere. Each part has its own symbol, shown in section 9.2. A drawing of a circuit shows the parts in one loop, with the wires joining them.

+-lamp lights
A drawing of a circuit: the cell on the left, the bulb on the right, and a closed switch on the bottom wire.
gap+-lamp does not light
A drawing of a circuit with a gap in the top wire. The gap breaks the loop.

Key ideas

  • A circuit drawing uses symbols for each part.
  • The cell has a long line and a short line.
  • The bulb is a circle with a cross inside.
  • The parts of a series circuit lie in one loop.
Worked example 9.4.1
In the circuit drawing with a closed switch, which side is the cell on: left or right? Write the word.

Method. Look at the drawing.

  1. Look at the drawing. The cell is drawn on the left-hand wire.
    left
  2. Write the side. So the cell is on the left.
    left
  3. Write the answer.
    left

Check. The bulb is on the right in the same picture. ✓

Worked example 9.4.2
Which symbol is a circle with a cross inside? Write the name of the part.

Method. Think about the symbols.

  1. Look at the symbols. A bulb is drawn as a circle with a cross inside.
    circle with a cross
  2. Name the part. So that symbol is a bulb.
    bulb
  3. Write the answer.
    bulb

Check. The cell symbol is different. ✓

Worked example 9.4.3
In the drawing with a gap in the top wire, does the lamp light? Write yes or no.

Method. Look for the gap in the loop.

  1. Look at the top wire. The top wire has a gap, so the loop is broken.
    gap
  2. Decide. A broken loop means the lamp does not light, so the answer is no.
    no
  3. Write the answer.
    no

Check. Closing the gap would complete the loop. ✓

Watch out

Watch out: a drawing with a gap in one wire is not a complete loop. The lamp will not light, even though all the parts are in the drawing.

Try it at home or school (with a grown-up). On paper, with a grown-up, draw a circuit with a cell, a bulb, a switch and two wires in one loop. Use the symbols from section 9.2. Check that the loop has no gap.

Exam tip

Grown-up tip. Ask: “Does your loop go all the way round? Which symbol is the switch?” Let your child draw the loop slowly, and check it with a finger.

Exercise 9D  Drawing and reading a circuit

1
FIn the circuit drawing with a closed switch, which side is the cell on: left or right? Write the word.
2
FIn the same circuit drawing, which side is the bulb on: left or right? Write the word.
3
FWhich symbol has a long line and a short line? Write the name of the part.
4
FWhich symbol is a circle with a cross inside? Write the name of the part.
5
FWhich symbol shows a switch that can be opened or closed? Write the name of the part.
6
FIn a series circuit, how many loops are there? Write the number.
7
FIn a series circuit, does every part lie in the same loop? Write yes or no.
8
PSLook at the drawing with a gap in the top wire in section 9.4. Does the lamp light? Write yes or no.
9
PSWhich part must be closed for the lamp to light in a circuit with a gap? Write the name of the part.
10
PSWorking scientifically. Predict what happens if the cell is taken out of a circuit with a lamp. Write one prediction with a reason.
11
RExplain how to read the symbols in a circuit drawing. Write one sentence.
9.5

More cells and the brightness of a lamp

Year 4
E2 and E3 practice: build a simple series circuit and test what changes the lamp (non-statutory extension)
Video lesson: More cells and the brightness of a lampComing soon
Story. Sam and Aisha test their lamp with one cell, and then with two cells. “The second one looks brighter,” says Aisha. Mr Patel says, “Good. Make sure only the number of cells changes, and keep the bulb, the wires and the holder the same.”

In a series circuit, a second cell adds more push to the electricity. With two cells, more electricity flows through the lamp, so the lamp is brighter. The fair test changes only the number of cells.

The table shows the results of the fair test, with one cell and with two cells.

Number of cells in the circuitBrightness of the lamp
1dim
2brighter

Key ideas

  • A series circuit with two cells gives a brighter lamp than one cell.
  • In a fair test, change only the number of cells.
  • Keep the bulb, the wires and the holder the same.
  • This is practice: the statements are about the loop, not the number of cells.
Worked example 9.5.1
In the table in section 9.5, how bright is the lamp with one cell? Write the word: dim or brighter.

Method. Read the table.

  1. Read the row. The row for one cell says the lamp is dim.
    dim
  2. Check the other row. The row for two cells says brighter, so the one-cell lamp is the dimmer one.
    dimmer
  3. Write the answer.
    dim

Check. One cell gives the dimmer lamp. ✓

Worked example 9.5.2
How many more cells are there in the second test than in the first? Write the number.

Method. Subtract the first number of cells from the second.

  1. Read the numbers. The first test has 1 cell, and the second has 2 cells.
    2 and 1
  2. Subtract. 2 minus 1 is 1.
    1
  3. Write the answer.
    1

Check. Check: 1 plus 1 makes 2. ✓

Worked example 9.5.3
Which test has the brighter lamp: one cell or two cells? Write the number of cells.

Method. Compare the two brightness words.

  1. Read the table. The row with two cells says brighter.
    brighter
  2. Choose the number. So two cells give the brighter lamp.
    2
  3. Write the answer.
    2

Check. Two cells gives more electricity through the lamp. ✓

Watch out

Watch out: a second cell does not make a bulb brighter if the loop is broken. The loop must be complete first.

Try it at home or school (with a grown-up). With a grown-up, make a complete loop with one cell and a bulb holder. Then add a second cell in the same line, and watch the bulb. Keep the wires and the bulb the same. Do not touch the bulb while it is hot.

Exam tip

Grown-up tip. Ask: “What did you change? What did you keep the same?” Let your child change only the number of cells, and compare the brightness.

Exercise 9E  More cells and the brightness of a lamp

1
FIn the table in section 9.5, how bright is the lamp with one cell? Write the word: dim or brighter.
2
FIn the table in section 9.5, how bright is the lamp with two cells? Write the word: dim or brighter.
3
FHow many more cells are in the second test than in the first? Write the number.
4
FWhich test has the brighter lamp? Write the number of cells.
5
FWrite the number of cells in the dim test. Write the number.
6
FIn a series circuit, does a second cell make the lamp brighter? Write yes or no.
7
FName the item that holds a bulb safely in a practical. Write the words.
8
FHow many cells does a circuit with one cell, one bulb and wires have? Write the number.
9
PSSam says two cells always make the lamp break. Is Sam right? Write yes or no.
10
PSRuby uses two cells and a lamp in a complete loop. Is the lamp brighter than with one cell? Write yes or no.
11
PSWorking scientifically. Plan a fair test to see how the number of cells changes the brightness. Write one thing that must stay the same.
12
RExplain why the lamp is dim with only one cell. Write one sentence.

Chapter summary

SkillMethod
AppliancesMany appliances run from the mains, such as kettles and televisions. Torches and remote controls run from cells.
Parts of a circuitA series circuit has a cell, wires, a bulb, a switch and a buzzer, all in one loop.
Complete loopA lamp lights only when it is part of a complete loop with the cell. A gap or an open switch breaks the loop.
SymbolsA cell has a long line and a short line. A bulb is a circle with a cross inside. A switch is a line that can be opened.
SafetyNever touch mains electricity. Practicals use cells and a bulb holder, with a grown-up.

Can you…?

  • I can name appliances that run from the mains, and those that run from cells
  • I can name the basic parts of a series circuit: cell, wires, bulb, switch and buzzer
  • I can say whether a lamp will light, using the idea of a complete loop
  • I can explain how a gap or an open switch breaks the loop
  • I can read the symbols for a cell, a bulb and a switch in a circuit drawing
  • I can follow safe practice with cells and a bulb holder

Key terms

appliance
a machine that uses electricity to do a job
mains
the electricity supply in a wall socket, which is dangerous to touch
cell
a battery, which pushes the electricity round a circuit
circuit
a loop that electricity can flow round, through a cell, wires and other parts
series circuit
a circuit in which all the parts are in one loop
complete loop
a loop with no gaps, so the electricity can flow all the way round
switch
a part that opens or closes the loop, to turn the circuit off or on
buzzer
a part that makes a sound when electricity flows through it
bulb holder
a holder that keeps the bulb in place safely in a practical

Exercise 9Z  Check-up

1
Name a common appliance that runs from the mains, from the table in section 9.1.
2
Which part of a circuit pushes the electricity round the loop? Write the name.
3
Which part turns the circuit on or off? Write the name.
4
In a complete loop with a cell, wires and a lamp, does the lamp light? Write yes or no.
5
A wire has a gap in it. Does the lamp light? Write the words: lights or does not light.
6
Does a lamp light when the switch is closed? Write yes or no.
7
Which symbol has a long line and a short line? Write the name of the part.
8
In a series circuit, how many loops are there? Write the number.
9
Ruby says a lamp lights if it touches one wire. Is Ruby right? Write no, and give one reason.
10
Explain why a switch is useful in a circuit. Write one sentence.

Total 15 marks. Allow about 15 minutes.

Exercise 9X  Practice test questions

1
FName one appliance that runs from cells, and not from the mains. Write one name.[1 mark]
2
FWhich part of a circuit turns the circuit on or off? Write the name.[1 mark]
3
FA lamp lights only when it is part of a ___ loop with the cell. Write the word.[1 mark]
4
FWhich part of a circuit pushes the electricity round the loop? Write the name.[1 mark]
5
FWhich part carries electricity from one part of the circuit to the next? Write the word.[1 mark]
6
FA circuit has a cell, a bulb, a switch and wires. The switch is open. Does the lamp light? Write the words: lights or does not light.[2 marks]
7
FWrite two appliances that run from the mains, from the list of appliances in the chapter.[2 marks]
8
FWhich symbol is a circle with a cross inside? Write the name of the part.[1 mark]
9
RExplain why a lamp does not light when there is a gap in a wire. Write one sentence.[3 marks]
10
FA circuit has a cell, a switch and a lamp, all in one loop. The switch is closed. Write the words: lights or does not light.[2 marks]
← Chapter 8: SoundChapter 10: Switches, conductors and insulators →

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