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New
New
Year 10
AQA
Foundation

Potential divider circuits

I can calculate p.d. across one of two components in a series circuit with a battery.

icon-background-square
New
New
Year 10
AQA
Foundation

Potential divider circuits

I can calculate p.d. across one of two components in a series circuit with a battery.

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Lesson details

Key learning points

  1. The p.d. across a component in an electric circuit measures the size of push that is moving current through it.
  2. The p.d. across each component in a series circuit adds up to the p.d. across the battery.
  3. The current is the same through every component in a series circuit.
  4. The larger the total resistance of a series circuit, the smaller the current through it.
  5. In a series circuit, the share of p.d. across each component is proportional to its resistance.

Keywords

  • Series circuit - an electrical circuit with a single loop

  • Potential difference (p.d.) - a measure of the push an electric field gives to charges

  • Resistance - a property of a material that opposes the flow of current

  • Potential divider - a series circuit that divides the p.d. across a power supply into two or more smaller voltages

Common misconception

A battery pushes a constant current around a circuit.

Provide opportunity for pupils to measure p.d. across a power supply when the resistance of a circuit it is connected to is altered.

For the practical included in this lesson, a power pack set to 3 V gives better results than a 3 V battery. This is because the internal resistance of the battery can affect results, which is a concept introduced in A–level physics.
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Teacher tip

Equipment

variable resistor, lamp, power supply, two voltmeters, electrical leads

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

6 Questions

Q1.
What is this electrical component?
An image in a quiz
Correct answer: a fuse
a resistor
a heater
a cell
Q2.
What currents will be able to pass through this component?
An image in a quiz
Correct answer: 1 A
Correct answer: 3 A
6 A
10 A
Q3.
In this model of a metal lattice, what do the black circles represent?
An image in a quiz
electrons
neutrons
protons
Correct answer: ions
Q4.
In this model of a metal lattice, what do the small blue circles represent?
An image in a quiz
Correct answer: electrons
neutrons
protons
ions
Q5.
What is the total resistance of these resistors when they are joined together?
An image in a quiz
1 Ω
2 Ω
3 Ω
Correct answer: 7 Ω
Q6.
A current of 0.3 A flows through these resistors. What is the p.d. across the 3 Ω resistor?
An image in a quiz
0.1 V
0.3 V
Correct answer: 0.9 V
1.5 V

6 Questions

Q1.
Which of these statements is correct about the p.d. across components in a series circuit?
a component with a higher resistance will have a lower p.d. across it
Correct answer: a component with a higher resistance will have a higher p.d. across it
Correct answer: a component with a lower resistance will have a lower p.d. across it
a component with a lower resistance will have a higher p.d. across it
Q2.
What is the p.d. across the 3 Ω resistor if the p.d. across the three resistors is 15 V?
An image in a quiz
3 V
6 V
Correct answer: 9 V
12 V
Q3.
What is the p.d. across the 20 Ω resistor?
An image in a quiz
1 V
2 V
3 V
Correct answer: 4 V
Q4.
What is the current through the 10 Ω resistor?
An image in a quiz
0.1 A
Correct answer: 0.2 A
0.3 A
0.6 A
Q5.
What is correct about a potential divider circuit with two resistors, one that has a lower resistance than the other?
the p.d. across the lower value resistor is higher
the p.d. across both resistors is the same
Correct answer: the p.d. across the lower value resistor is lower
Q6.
Which of these components would be used in a dimmer switch?
a diode
a buzzer
Correct answer: a variable resistor
a voltmeter

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