AQA GCSE Physics Physics Paper 1 (Higher), June 2024: Question 3
9 marks · Standard Demand difficulty · Extended Answer
Describe a method to investigate how the length of a wire affects its resistance, identify the correct graph showing this relationship, and explain why a 1.50 V cell is not an electrical hazard.
Practise this questionQuestion
Question text
03 A student investigated how the length of a wire affects the resistance of the wire at
constant temperature.
Figure 3 shows the circuit used.
Figure 3
03.1 The student plotted a graph of resistance against the length of wire.
Describe a method the student could have used to collect the data needed to
plot the graph.
[6 marks]
03.2 Which graph shows the relationship between the resistance of a wire at constant
temperature and its length?
[1 mark]
Tick ( ) one box.
03.3 The student used a cell that had a potential difference of 1.50 V.
Explain why the cell was not an electrical hazard to the student in the investigation.
[2 marks]
Mark scheme
Show the mark scheme
Question 3
AO /
Question Answers Mark
Spec. Ref.
03.1 Level 3: The method would lead to the production of a valid 5–6 AO1
outcome. The key steps are identified and logically sequenced. 4.2.1.3
RPA3
Level 2: The method would not necessarily lead to a valid 3–4
outcome. Most steps are identified, but the method is not fully
logically sequenced.
Level 1: The method would not lead to a valid outcome. Some 1–2
relevant steps are identified, but links are not made clear.
No relevant content 0
Indicative content
• measure the length of the wire (between the crocodile clips)
using the ruler
• length varied by moving crocodile clips
• current measured with ammeter
• potential difference measured with voltmeter
• calculate resistance for each length
• use V = IR to calculate resistance
• record current and pd for different lengths
• repeat readings of current and pd for each length and mean
values calculated
• remove any anomalous readings
• ensure values of current are low to minimise heating of wire
• ensure circuit is disconnected between readings
Level 2:
Varying the length of the wire. Measurements / equipment needed
for pd and current.
AO /
Question Answers Extra information Mark
Spec. Ref.
03.2 1 AO1
4.2.1.3
4.2.1.4
RPA3
– – –
AO /
Spec. Ref.
03.3 potential difference is (very) low 1 AO1 11
(so) no risk of electric shock allow less risk of electric shock 1 AO3
or
(so) no risk of electrocution 4.2.1.3
allow so wire won’t melt RPA3
allow so wire won’t get hot
Total Question 3 9
How to answer it
Investigation: Resistance and Length of a Wire
What this question tests
This question assesses your knowledge of Required Practical Activity 3 (RPA3): investigating how the length of a wire affects its electrical resistance. It tests your ability to write a structured scientific method, interpret proportional graph trends, and understand basic electrical safety in low-voltage circuits.
Describing a Method for Investigating Resistance
✅ Marking Strategy (Level 3: 5–6 Marks)
To secure top marks, your method must be logically sequenced and detailed enough for someone else to replicate and obtain valid results. Key requirements include:
- Measuring wire length using a ruler/metre rule between crocodile clips.
- Varying the length by moving the crocodile clips.
- Measuring potential difference (pd) with a voltmeter and current with an ammeter.
- Using the equation R = V / I to calculate resistance.
- Repeating measurements to calculate mean values and discounting anomalies.
- Precautions to prevent heating (e.g., opening the switch between readings).
🧠 Exam Technique (6-Mark Paragraphs)
For extended writing questions:
- Use bullet points or clear sequential steps (First, Next, Then).
- Always state how equipment is used (e.g., "measure length with a ruler"). Never just list equipment names.
- Always link measurements to the final calculation: state that you measure V and I, then calculate R using R = V / I .
❌ Common Errors
- Forgetting to mention the power supply: Leaving the circuit connected continuously, causing the wire to heat up and change its resistance.
- Vague measurements: Saying "measure the wire" instead of "measure the length of wire between the crocodile clips".
- Omitting repeats: Failing to mention taking repeat readings to find a mean.
Interpreting the Graph of Resistance vs. Length
✅ Correct Answer
Tick the third graph showing a straight line passing through the origin (directly proportional relationship).
💡 Key Knowledge
The resistance of a metallic wire is directly proportional to its length ( R ∝ l ). If you double the length of the wire, the resistance doubles. Therefore, the line must be straight and go through (0,0) .
Explaining Electrical Safety
✅ Correct Answers (2 Marks)
Any two valid points from the mark scheme:
- The potential difference is very low (1.50 V).
- There is no risk of electric shock / electrocution.
- *Alternative accepted points:* The wire will not get hot / melt.
🧠 Exam Technique
When a question asks why something is not a hazard, link the property of the equipment (e.g., "1.50 V is low") directly to the consequence (e.g., "current is small, so no risk of shock"). Do not just repeat the question stem.
Topics
Physics · Required Practicals · P2: Electricity · Required Practicals
Question and mark scheme from the AQA GCSE Physics examination, Physics Paper 1 (Higher), June 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.