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Year 9

Voltage in parallel circuits

I can describe the rule for voltages in a parallel circuit.

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New
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Year 9

Voltage in parallel circuits

I can describe the rule for voltages in a parallel circuit.

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Share activities with pupils
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Lesson details

Key learning points

  1. A voltmeter is connected to each side of a battery or component.
  2. Voltage (or potential difference) is measured in volts (V).
  3. The voltage across a battery measures the strength with which it can ‘push’ current around a circuit.
  4. The voltage across a component in an electric circuit measures the size of ‘push’ that is moving current through it.
  5. The voltage across each branch of a parallel circuit is the same as the voltage across the battery.

Keywords

  • Voltmeter - A voltmeter is a device that is connected in parallel with components to measure the voltage across them.

  • Voltage - The voltage across a component measures the size of the 'push' that is moving current through it.

  • Potential difference - Potential difference is a more formal term for voltage, however they can be used interchangeably because they refer to the same electrical quantity.

  • Parallel circuit - A circuit with junctions and separate loops is a parallel circuit.

  • Branch - Each separate loop in a parallel circuit can be called a branch.

Common misconception

Voltage in a parallel circuit is shared out between each branch of the circuit.

Provide opportunity for pupils to measure voltage across each branch of a range of parallel circuits to give evidence for the correct rule.

Pupils should understand a rule for voltage in parallel circuits in order to understand how current flows through each branch in a parallel circuit. This rule is covered in this lesson and ‘Loops of a parallel circuit’. These two lessons should be completed before 'Currents in a parallel circuit'.
Teacher tip

Equipment

For each group: voltmeter, connecting wires (×8), 1.5 V battery (×3), bulb, buzzer, motor and resistor.

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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Starter quiz

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6 Questions

Q1.
Which of the following statements about series circuits is correct?
There are junctions.
Correct answer: There is only one loop.
The current can flow in different branches.
The current is higher in some components.
Q2.
Which of the following statements about parallel circuits is correct?
Correct answer: There are junctions.
There is only one loop.
The current is the same everywhere in the circuit.
The current always splits equally at a junction.
Q3.
Which of the following statements about the junctions in a parallel circuit are correct?
The current is the same in all branches at a junction.
Correct answer: The current can split at a junction.
Correct answer: The current can join up at a junction.
Some branches at a junction get no current.
Q4.
When building a parallel circuit, which of the following statements describes the most effective method to use?
Always start at the battery.
Always go anticlockwise.
The components must be exactly in the positions shown on the circuit diagram.
Correct answer: Complete each loop one at a time.
Q5.
Which of the following statements about circuit diagrams is correct?
Small gaps are permitted.
The battery must point to the right.
Correct answer: Straight horizontal and vertical lines are needed.
A variety of symbols or pictures can be used for a single component.
Q6.
A real parallel circuit is made using a circuit diagram for reference. Which of the following statements is correct?
The components must be in the same positions as the diagram.
Correct answer: The number of components and loops will be the same.
The circuit and the diagram will look exactly the same.

Exit quiz

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6 Questions

Q1.
Which of the following devices measures the 'push' that a battery gives to current?
an ammeter
a newton meter
Correct answer: a voltmeter
a joulemeter
Q2.
Which of the following statements correctly describe how voltmeters should be connected?
Correct answer: In parallel to the component they are measuring.
In series with the component they are measuring.
Before the component they are measuring.
After the component they are measuring.
Q3.
What will happen to the lamps in the circuit shown when the circuit is connected?
An image in a quiz
Correct answer: only lamp 1 will light
only lamp 2 will light
both lamps will light
lamp 1 will be bright and lamp 2 will be dim
Q4.
What is the voltage across the lamp if the voltage of the battery is 1.5 V?
An image in a quiz
0.5 V
0.75 V
Correct answer: 1.5 V
3.0 V
Q5.
What is the voltage across the battery of two cells if the voltage across the resistor is 2.0 V and across the motor is 2.0 V?
An image in a quiz
1.0 V
Correct answer: 2.0 V
4.0 V
6.0 V
Q6.
What is the voltmeter measuring?
An image in a quiz
The voltage across the resistor only.
The voltage across the lamp only.
The voltage across the resistor and lamp only.
Correct answer: The voltage across the resistor, the lamp and the battery.