AQA A-Level Physics Paper 1, June 2024: Question 27

1 mark · Medium difficulty · Multiple Choice

Calculate the potential difference across a 12 ohm resistor connected across a battery of emf 2.0 V and internal resistance 4.0 ohm.

Practise this question

Question

Multiple choice question 27. A 12 ohm resistor is connected across the terminals of a battery of emf 2.0 V and internal resistance 4.0 ohm. What is the pd across the resistor? Options are A: 0.25 V, B: 0.75 V, C: 1.30 V, D: 1.50 V.
Question text

27 A 12 Ω resistor is connected across the terminals of a battery of emf 2.0 V and internal

resistance 4.0 Ω.

What is the pd across the resistor?

[1 mark]

A 0.25 V

B 0.75 V

C 1.30 V

D 1.50 V

Mark scheme

Show the mark scheme Mark scheme for question 27 showing the correct answer is D, with a value of 1.50 V.

27 D 1.50 V AO2

How to answer it

Terminal Potential Difference Calculation

What this question tests

This question assesses your understanding of sources of electromotive force (emf), internal resistance, and how potential difference is distributed across a simple closed circuit containing a single load resistor.

Question 27 Analysis

Multiple Choice Question (1 Mark)

✅ Correct Answer

Option D: 1.50 V

Marks awarded: 1 / 1 (AO2 - Application)

💡 Key Knowledge

  • Emf ( E ) is shared between the load resistor ( V ) and the internal resistance ( Ir ).
  • Formula: E = V + Ir or using potential divider principles.

🧠 Exam Technique

You can solve this rapidly using the potential divider formula, bypassing the need to calculate circuit current first!

❌ Common Errors

Students often mistake the internal resistance for part of the external circuit or incorrectly calculate the total resistance by subtracting instead of adding.

📐 Step-by-Step Calculation

Method 1: Potential Divider approach (Fastest)

  1. Identify components: Load resistance R = 12 ohm , internal resistance r = 4.0 ohm , emf E = 2.0 V .
  2. Apply the voltage divider equation for the pd across the load resistor ( V ):
    V = E × [ R / (R + r) ]
  3. Substitute the values:
    V = 2.0 × [ 12 / (12 + 4.0) ]
  4. Simplify:
    V = 2.0 × (12 / 16) = 2.0 × 0.75 = 1.50 V

Method 2: Current approach (Alternative)

  1. Find total resistance: R_total = R + r = 12 + 4.0 = 16 ohm .
  2. Calculate circuit current: I = E / R_total = 2.0 / 16 = 0.125 A .
  3. Calculate pd across the resistor: V = I × R = 0.125 × 12 = 1.50 V .

Topics

Physics · 3.5 Electricity

Question and mark scheme from the AQA A-Level Physics examination, Paper 1, June 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.