AQA GCSE Physics Physics Paper 1 (Foundation), June 2024: Question 2
10 marks · Standard Demand difficulty · Short Answer
Calculate the resistance of a coin from its potential difference and current, and analyze thermistor characteristics in a series circuit.
Practise this questionQuestion
Question text
02 Figure 4 shows a student putting a coin into a vending machine that sells food.
Figure 4
The vending machine is connected to the mains electricity supply.
02.1 What is the frequency of the mains electricity supply in the UK?
[1 mark]
Tick ( ) one box.
50 hertz
60 hertz
100 hertz 9
02.2 What is the potential difference of the mains electricity supply in the UK?
[1 mark]
Tick ( ) one box.
12 volts
230 volts
20 000 volts
The vending machine identifies the value of the coin by measuring the resistance of
the coin.
02.3 The machine applies a potential difference of 0.45 V across the coin.
The current in the coin is 0.75 A.
Calculate the resistance of the coin.
Use the equation:
potential difference
resistance =
current
[2 marks]
Resistance = Ω
The temperature inside the vending machine is monitored using an electrical circuit.
Figure 5 shows part of the circuit.
Figure 5
02.4 The circuit symbol for the thermistor is wrong.
What is the circuit symbol for a thermistor?
[1 mark]
Tick ( ) one box.
02.5 How could the potential difference (pd) across the resistor be calculated?
[1 mark]
Tick ( ) one box.
pd across battery – pd across thermistor
pd across battery + pd across thermistor
pd across battery × pd across thermistor
pd across battery ÷ pd across thermistor
02.6 At one temperature, the thermistor in Figure 5 has a resistance of 200 Ω.
What is the potential difference across the thermistor at this temperature?
Give a reason for your answer.
[2 marks]
Tick ( ) one box.
0.0 V
1.0 V
1.5 V
2.0 V
Reason
Figure 6 shows how the resistance of the thermistor varies with temperature.
Figure 6
02.7 When the temperature of the thermistor is 10 °C, the resistance of the thermistor
is 600 Ω.
Calculate the change in resistance when the temperature increased from
10 °C to 15 °C.
[2 marks]
Change in resistance = Ω
Mark scheme
Show the mark scheme
Question 2
AO /
Question Answers Extra information Mark
Spec. Ref.
02.1 50 hertz 1 AO1
4.2.3.1
AO /
Spec. Ref.
02.2 230 volts 1 AO1
4.2.3.1
AO /
Spec. Ref.
02.3 0.45 1 AO2
resistance = 4.2.1.3
0.75
resistance = 0.60 (Ω) 1
AO /
Spec. Ref.
02.4 1 AO1
4.2.1.1
AO /
Spec. Ref.
02.5 pd across battery - pd across 1 AO3
thermistor – – – 4.2.2
AO /
Spec. Ref.
02.6 1.5 V 1 AO3
4.2.2
(thermistor has the) same MP2 dependent on scoring MP1 1
resistance as resistor
or
both (components) have a allow pd shared equally
resistance of 200 (Ω) (between components of equal
resistance)
allow pd will be half (of the total
pd)
AO /
Spec. Ref.
02.7 resistance at 15 °C = 200 (Ω) 1 AO2
4.2.1.4
change in resistance = 400 (Ω) allow a correct change in 1
resistance from a misread
resistance within the range 180
to 220 Ω
Total Question 2 10
How to answer it
Vending Machine Circuits Study Guide
What this question tests
This exam question tests your core knowledge of mains electricity values in the UK, circuit symbol recognition, and the application of resistance equations. It also checks your ability to analyse series circuits, potential difference (pd) sharing across components, and how to accurately interpret data from a resistance-temperature graph for a thermistor.
Part 02.1: Mains Frequency
✅ Correct Answer
Tick: 50 hertz
💡 Key Knowledge
- The UK mains electricity supply operates at a frequency of 50 Hz.
- Frequency is the number of complete cycles alternating per second.
Part 02.2: Mains Potential Difference
✅ Correct Answer
Tick: 230 volts
💡 Key Knowledge
- The standard domestic mains potential difference in the UK is 230 V.
- Be careful not to confuse this with older syllabus values (like 240 V) or transformer values.
Part 02.3: Calculating Resistance
📐 Calculation Steps
- State the equation: resistance = potential difference ÷ current
- Substitute values: resistance = 0.45 ÷ 0.75
- Calculate final answer: 0.60 (Ω)
🧠 Exam Technique & Errors
- Units: Make sure to include ohms (Ω) if not already provided on the answer line.
- Common Error: Inverting the formula (dividing current by pd instead). Always check the equation given on the paper!
Part 02.4: Thermistor Circuit Symbol
✅ Correct Answer
Tick the box showing a rectangle with a diagonal line running through it (the standard thermistor symbol).
❌ Common Errors
Students frequently confuse the thermistor symbol with a variable resistor (arrow through a rectangle) or a light-dependent resistor (LDR, circle with arrows pointing inwards).
Part 02.5: Potential Difference in Series
✅ Correct Answer
Tick: pd across battery − pd across thermistor
💡 Key Knowledge
In a series circuit, the total potential difference supplied by the battery is shared between all the components. Therefore, the pd across one component is the total battery pd minus the pd across the other component.
Part 02.6: Thermistor Potential Difference & Reasoning
📐 Correct Answer & Calculation
Value: 1.5 V
Reason: The thermistor has the same resistance as the resistor (both are 200 Ω), so the potential difference is shared equally across both components.
🧠 Examiner Insight
Mark point 2 (the reason) is strictly dependent on scoring mark point 1. You cannot get the reasoning mark if your numerical value is wrong. Mentioning that resistances are equal is key.
Part 02.7: Graph Interpretation & Change in Resistance
📐 Step-by-Step Working
- Find resistance at 10 °C: Given in question as 600 Ω (or read from graph).
- Find resistance at 15 °C: Use the curve on Figure 6 to find the resistance at 15 °C, which is 200 Ω.
- Calculate the change: 600 Ω − 200 Ω = 400 (Ω)
🧠 Exam Technique & Allowances
- Graph reading tolerance: Examiners allow a correct change in resistance calculated from a misread value as long as your reading at 15 °C falls within the accepted range (180 to 220 Ω).
- Always use a sharp pencil and ruler when reading values off graphs to avoid parallax errors!
Topics
Physics · P2: Electricity
Question and mark scheme from the AQA GCSE Physics examination, Physics Paper 1 (Foundation), June 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.