AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
The greater the resistance of the component the smaller the current for a…
Full specification wording
Current, resistance and potential difference: The greater the resistance of the component the smaller the current for a given potential difference (pd) across the component.
For a fixed potential difference, current and resistance work against each other: double the resistance and the current halves, because I = V ÷ R. That single relationship explains most circuit…
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 2 of 4
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
For a fixed potential difference, current and resistance work against each other: double the resistance and the current halves, because I = V ÷ R. That single relationship explains most circuit questions. Close a switch that brings a second heating element into parallel and the total resistance of the circuit falls, so the current from the battery rises, and since the potential difference across the battery is unchanged the power output rises too, because P = I V. Add resistors in series instead and the total resistance increases, so the current falls. The same reasoning explains why a long thin wire passes a smaller current than a short thick one of the same material at the same potential difference.
What earns the marks
- Stating that a greater resistance gives a smaller current at the same potential difference.
- Identifying whether the total resistance of the circuit rises or falls in the situation described.
- Deducing the resulting change in current.
- Linking that change to the power output using P = I V with the pd unchanged.
Common mistakes and how to put them right
Saying that adding a parallel branch increases the total resistance.
Assuming the potential difference across the battery changes when a switch is closed.
Reversing the relationship, so claiming more resistance means more current.
Quoting P = I² R without any quantitative comparison, which the mark scheme ignores.
Exam tips
- Work through the chain in order: total resistance, then current, then power, each with its reason.
- The second mark usually depends on the first, so an error about the resistance costs the rest.
- State explicitly that the supply potential difference stays the same, because it is often the missing step.
Try the lesson
The start of the Current, resistance and potential difference: The greater the resistance of the component the smaller the current for a given potential difference (pd) across the component. lesson, made from checked teaching notes for this specification point.
Have a go first
Two resistors are each connected across the same 6 V supply. Resistor A has a resistance of 2 Ω and resistor B has a resistance of 6 Ω. Which resistor has the smaller current through it?
Listen
For a fixed potential difference, current and resistance work against each other: double the resistance and the current halves, because I = V ÷ R. That single relationship explains most circuit questions. Close a switch that brings a second heating element into parallel and the total resistance of the circuit falls, so the current from the battery rises, and since the potential difference across the battery is unchanged the power output rises too, because P = I V. Add resistors in series instead and the total resistance increases, so the current falls. The same reasoning explains why a long thin wire passes a smaller current than a short thick one of the same material at the same potential difference. A strong answer earns marks for these points. stating that a greater resistance gives a smaller current at the same potential difference. identifying whether the total resistance of the circuit rises or falls in the situation described. deducing the resulting change in current. linking that change to the power output using P = I V with the pd unchanged. Exam tip: Work through the chain in order: total resistance, then current, then power, each with its reason.
Key words
Say what each word means before you turn the card.
inverse relationship
Try answering aloud or in your head before turning the card.
total resistance
Try answering aloud or in your head before turning the card.
series and parallel effects
Try answering aloud or in your head before turning the card.
current and power
Try answering aloud or in your head before turning the card.
See every definition
- inverse relationship
- For a fixed potential difference, the greater the resistance of the component the smaller the current, so current and resistance work against each other.
- total resistance
- Adding resistors in series increases it, so the current falls, while bringing a second heating element into parallel makes it fall, so the current from the battery rises.
- series and parallel effects
- A parallel branch lowers the total resistance and raises the current, whereas resistors added in series raise the total resistance and lower the current.
- current and power
- Since the potential difference across the battery is unchanged, a rise in current raises the power output too, because P = I V.
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of Current, resistance and potential difference: The greater the resistance of the component the smaller the current for a given potential difference (pd) across the component.
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge