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Year 10
AQA
Higher

Linking current, potential difference and resistance

I can describe the relationships between current, potential difference and resistance.

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Year 10
AQA
Higher

Linking current, potential difference and resistance

I can describe the relationships between current, potential difference and resistance.

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Lesson details

Key learning points

  1. The current in a series circuit is the same everywhere.
  2. The p.d. across each component in a series electric circuit adds up to the p.d. of the battery.
  3. The greater the resistance in a series circuit, the lower the current (current is inversely proportional to resistance).
  4. The greater the battery p.d. in series circuit, the larger the current (current is directly proportional to p.d.).
  5. Current, p.d. or resistance can be calculated with the equation: current = p.d./resistance.

Keywords

  • Series circuit - a circuit where there is only one loop

  • Potential difference (p.d.) - the voltage or a measure of the ‘push’ on electrons in a circuit

  • Resistance - a measure of how difficult it is for current to flow in a circuit

  • Electrical current - a measure of the amount of charge passing a given point in one second

  • Ohms (Ω) - the unit of resistance

Common misconception

Pupils often use physics equations without understanding, leading to errors.

Develop a qualitative understanding of potential difference, current and resistance before combining them mathematically. Use the equation as a shorthand for an already understood relationship between them.


To help you plan your year 10 physics lesson on: Linking current, potential difference and resistance, download all teaching resources for free and adapt to suit your pupils' needs...

Provide opportunity for pupils to explain what they think is likely to happen in a range of different circuit examples before they calculate their answers.
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This content is © Oak National Academy Limited (2025), 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.
The number of coulombs that flow past a point each second equals the…
charge.
Correct answer: current.
electric field strength.
force.
velocity.
Q2.
The unit of current is the…
Correct Answer: ampere, ampère, amp, amperes, amps
Q3.
A circuit which has only one loop is called a circuit.
Correct Answer: series
Q4.
In a circuit, electrons flow through the wires away from the end of the battery.
Correct Answer: negative, minus
Q5.
In a circuit with a single loop, which of the following statements are correct?
There is an electric field around the battery only.
Correct answer: There is an electric field around the whole circuit.
Electrons nearest the battery experience the most force.
Correct answer: Electrons experience the same force in all parts of the circuit.
Q6.
The equation relating current, charge and time is: current = charge ÷ time. Which of the following equations is the correct rearrngement of the equation with time as the subject?
Correct answer: time = charge ÷ current
time = current ÷ charge
time = current × charge

Exit quiz

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6 Questions

Q1.
Match the following quantities to its definition.
Correct Answer:resistance,a measure of how difficult it is for charge to move around a circuit
tick

a measure of how difficult it is for charge to move around a circuit

Correct Answer:current,the amount of charge passing a point in one second
tick

the amount of charge passing a point in one second

Correct Answer:potential difference,a measure of the ‘push’ on electrons in a circuit
tick

a measure of the ‘push’ on electrons in a circuit

Q2.
A series circuit contains only a cell and a lamp. Which of the following changes occurs if another lamp is added, in series with the first lamp?
Correct answer: The current in the circuit decreases.
The potential difference of the cell decreases.
The resistance of the circuit decreases.
Q3.
In a series circuit, there is a particular type of relationship between current and total resistance: the current is proportional to the total resistance, if the p.d. stays the same.
Correct Answer: inversely
Q4.
The potential difference across a 10 Ω resistor in a circuit is 4.0 V. What is the current in the resistor?
0.25 A
Correct answer: 0.40 A
2.5 A
40 A
Q5.
A motor has a resistance of 6.0 Ω. What p.d. is needed to make a current of 1.5 A flow through the motor?
0.25 V
0.75 V
4.0 V
Correct answer: 9.0 V
Q6.
A pupil has identical lamps and identical cells. He connects two cells and two lamps in series. Then he changes the circuit, but the current does not change. Which of the following could he have done?
Correct answer: added one cell and added one lamp
Correct answer: removed one cell and removed one lamp
removed one lamp and added one cell
removed one cell and added one lamp