AQA GCSE Physics Physics Paper 1 (Foundation), November 2021: Question 11

10 marks · Standard Demand difficulty · Extended Answer

Describe a method to investigate I-V characteristics of a resistor, explain the effect of temperature change on the results, determine the resolution of an ammeter, and state an advantage of a digital ammeter.

Practise this question

Question

A multi-part physics question about an investigation into current and potential difference. Figure 14 shows a circuit diagram with a power supply, switch, ammeter, variable resistor, and a resistor R connected in parallel with a voltmeter. Part 1.1 asks to describe a method for this investigation (6 marks). Part 1.2 asks to explain how increased temperature of resistor R affects results (2 marks). Figure 15 shows an analogue ammeter scale with readings from 0 to 2.0 A, and Part 1.3 asks for its resolution (1 mark). Figure 16 shows a digital ammeter reading 1.34 A, and Part 1.4 asks for another advantage of using a digital ammeter instead of an analogue one (1 mark).
Question text

11 Student A investigated how the current in resistor R at constant temperature varied

with the potential difference across the resistor.

Student A recorded both positive and negative values of current.

Figure 14 shows the circuit Student A used.

Figure 14

11.1 Describe a method that Student A could use for this investigation.

[6 marks]

11.2 Student B repeated the investigation.

During Student B’s investigation the temperature of resistor R increased.

Explain how the increased temperature of resistor R would have affected

Student B’s results.

[2 marks]

Figure 15 shows the scale on a moving coil ammeter at one time in the investigation.

Figure 15

11.3 What is the resolution of the moving coil ammeter?

[1 mark]

43 Resolution = A

*1411.*4 Student B replaced the moving coil ammeter with a digital ammeter.

Figure 16 shows the reading on the digital ammeter.

Figure 16

The digital ammeter has a higher resolution than the moving coil ammeter.

Give one other reason why it would have been better to use the digital ammeter

throughout this investigation.

[1 mark]

Mark scheme

Show the mark scheme The mark scheme provides a level-based response grid for the 6-mark method question requiring logical steps, ammeter/voltmeter usage, variable resistor control, and reversing polarity. Subsequent sections detail acceptable answers for temperature effects on resistance, the resolution value of 0.2 A, and advantages of digital ammeters such as no parallax error or less chance of misreading.

Question 11

AO/

Question Answers Mark

Spec. Ref

11.1 Level 3: The method would lead to the production of a valid AO1

5–6

outcome. All key steps are identified and logically sequenced. 4.2.1.4

RPA4

Level 2: The method would not necessarily lead to a valid

outcome. Most steps are identified, but the plan is not fully logically 3–4

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 current in R using the ammeter

• measure the p.d. across R using the voltmeter

• vary the resistance of the variable resistor

(or vary the number of cells or use a variable power supply)

• record a range of values of current and p.d.

• ensure current is low to avoid temperature increase

• switch circuit off between readings

• reverse connection of R to power supply

• repeat measurements of I and V in negative direction

• plot a graph of current against p.d.

AO /

Question Answers Extra information Mark

Spec. Ref.

11.2 current and p.d. would not be 1 AO3

directly proportional 4.2.1.4

or RPA4

I-V graph would not be straight

or

I-V graph would be curved

(because) resistance of R would 1

increase

11.3 0.2 (A) 1 AO3

4.2.2

RPA4

any one from:

11.4 1 AO3

• less chance of misreading 4.2.2

• no parallax error allow position of eye(s) does not

RPA4

affect reading

• it can give a reading closer to allow ‘it is more accurate’

the true value

ignore ‘no human error’

ignore ‘easier to read’

Total 10

How to answer it

Investigating Resistance, Current and Potential Difference (RPA 4)

What this question tests

This question assesses your knowledge of Required Practical Activity 4 (I-V characteristics), experimental design, controlling variables, interpreting meter scales (resolution), evaluating instrument types (digital vs analogue), and understanding the thermal effects of current on resistance.

Part (1.1.1) - Experimental Method

Describe a method that Student A could use for this investigation. [6 marks]

✅ Marking Strategy (Level 3: 5–6 marks)

To achieve top marks, your method must be logical, detailed, and cover both positive and negative values of current:

  • Measure current using the ammeter and potential difference (p.d.) using the voltmeter.
  • Vary the resistance of the variable resistor (or change the number of cells/power supply).
  • Record pairs of readings for current and p.d.
  • Switch the circuit off between readings to keep the temperature of resistor R constant.
  • Reverse the connections to the power supply to obtain negative values for current and p.d.
  • Plot a graph of current against potential difference.

🧠 Exam Technique & Structure

This is a 6-mark extended writing question marked using levels of response. Examiners look for a coherent, chronological set of instructions that another student could follow to successfully gather valid data.

Mark allocation: Level 3 (5–6 marks) requires a fully valid, logical method. Level 1 or 2 is given if key steps like reversing the supply or keeping temperature constant are omitted.

Part (1.1.2) - Thermal Effects on Resistance

Explain how the increased temperature of resistor R would have affected Student B's results. [2 marks]

✅ Correct Answer

Current and p.d. would not be directly proportional (or the I-V graph would be curved), because the resistance of resistor R would increase as it gets hotter.

💡 Key Knowledge

As electrical charge flows through a resistor, energy is transferred, causing the resistor to heat up. For a metallic conductor, higher temperature causes metal ions to vibrate more rapidly, increasing collisions with electrons and thus increasing resistance ($R = V / I$).

❌ Common Errors

Students often lose the second mark by stating the graph curves without explaining why (failing to link temperature increase to an increase in resistance).

Part (1.1.3) - Reading Instrument Resolution

What is the resolution of the moving coil ammeter? [1 mark]

✅ Correct Answer

0.2 A

💡 Key Knowledge

Resolution is the smallest change in a quantity being measured that gives a perceptible change in the reading. Looking at the scale between 0 and 1.0, there are 5 intervals, meaning each small division represents 1.0 / 5 = 0.2 A .

Part (1.1.4) - Digital vs Analogue Meters

Give one other reason why it would have been better to use the digital ammeter throughout this investigation. [1 mark]

✅ Acceptable Answers (Any one)

  • Less chance of misreading
  • No parallax error (allow position of eyes does not affect reading)
  • Can give a reading closer to the true value (more accurate)

❌ Common Errors to Avoid

Do not write vague statements like "no human error" or "easier to read". Be specific: digital meters eliminate parallax error caused by viewing an analogue needle from an angle.

Topics

Physics · Required Practicals · P2: Electricity · Required Practicals

Question and mark scheme from the AQA GCSE Physics examination, Physics Paper 1 (Foundation), November 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.