AQA GCSE Physics Physics Paper 1 (Higher), November 2020: Question 1

11 marks · Standard Demand difficulty · Short Answer

Investigate the I-V characteristics of a filament lamp using circuit diagrams, graphical analysis of experimental results, resistance calculations, and zero error definition.

Practise this question

Question

Question text

01 A student investigated how the current in a filament lamp varied with the potential

difference across the filament lamp.

Figure 1 shows part of the circuit used.

Figure 1

01.1 Complete Figure 1 by adding an ammeter and a voltmeter.

Use the correct circuit symbols. 4

[3 marks]

Figure 2 shows some of the results.

Figure 2

01.2 The student reversed the connections to the power supply and obtained negative

values for the current and potential difference.

Draw a line on Figure 2 to show the relationship between the negative values of

current and potential difference.

[2 marks]

01.3 Write down the equation which links current (I), potential difference (V) and

resistance (R).

[1 mark]

01.4 Determine the resistance of the filament lamp when the potential difference across it

is 1.0 V.

Use data from Figure 2.

[4 marks]

Resistance = Ω

01.5 A second student did the same investigation. The ammeter used had a zero error.

What is meant by a zero error?

[1 mark]

Mark scheme

Show the mark scheme

Question 1

AO /

Question Answers Extra information Mark

Spec. Ref.

01.1 ammeter and voltmeter symbols 1 AO1

correct 4.2.1.1

RPA 4

voltmeter in parallel with lamp 1

ammeter in series with lamp 1

01.2 smooth curved line of correct shape do not accept a line that 1 AO2

becomes horizontal 4.2.1.4

RPA 4

passing through - 4.0 V, - 0.2 A 2nd mark conditional on 1

or scoring 1st mark

– 6.0 V, - 0.23 A

01.3 potential difference = current × 1 AO1

resistance 4.2.1.3

or RPA 4

V = IR

01.4 AO2

I = 0.08 (A) 1 4.2.1.3

RPA 4

1.0 = 0.08 × R allow 1.0 = their I × R 1

provided their I has been

obtained from the graph

1.0 1.0 1

R = allow R =

0.08 their I

R = 12.5 (Ω) allow an answer consistent 1

with their I

Question Answers Extra information Mark AO /

Spec. Ref.

01.5 ammeter displays a reading 1 AO3

when not connected (to a circuit) 4.2.1.4

RPA 4

Total 11

How to answer it

Investigating Filament Lamps & Circuit Analysis

What this question tests

This question assesses your knowledge of Required Practical 4 (RPA 4): investigating electrical circuits. It tests your ability to correctly draw circuit diagrams with meters, plot and interpret graphical data in both positive and negative quadrants, recall and apply the equation linking potential difference, current, and resistance ($V = IR$), and define systematic measurement errors like zero errors.

Question 01.1

Adding Circuit Symbols (3 Marks)

✅ Correct Answer

An ammeter drawn in series with the lamp.
A voltmeter drawn in parallel across the lamp.
Correct standard physics symbols used for both meters.

💡 Key Knowledge

Ammeter: Measures current flowing through a component, so it must be placed directly in the main loop (in series).
Voltmeter: Measures potential difference across a component, so it must be connected on a separate branch around the lamp (in parallel).

🧠 Exam Technique

Always draw straight, clean lines using a ruler for connecting wires. Make sure your ammeter circle contains an A and your voltmeter circle contains a V .

❌ Common Errors

Students frequently lose marks by placing the voltmeter in series, or placing the ammeter in parallel which can cause a short circuit or damage the equipment due to low resistance.

Mark breakdown: 1 mark for correct ammeter symbol, 1 mark for correct voltmeter symbol, 1 mark for correct placement (series/parallel).

Question 01.2

Extrapolating Graph Data for Reversed Connections (2 Marks)

✅ Correct Answer

A smooth curved line reflecting the exact rotational symmetry of the positive side into the negative quadrant.
The line must pass accurately through -4.0 V, -0.2 A or -6.0 V, -0.23 A .

💡 Key Knowledge

Reversing the power supply reverses both the potential difference and current values (making them negative). The filament lamp behaves identically in reverse, producing an identical characteristic curve flipped into the third quadrant.

🧠 Exam Technique

Turn your exam paper upside down if it helps you draw a smooth curve downwards through the origin matching the shape of the top curve. Do not use straight lines or let the curve flatten out horizontally.

❌ Common Errors

Drawing straight lines between plotted points instead of a smooth curve, or flattening the curve into a horizontal line at high negative values.

Mark breakdown: 1 mark for smooth curved line of correct shape, 1 mark (conditional) for passing through the key coordinate points.

Question 01.3

Equation Linking V, I, and R (1 Mark)

✅ Correct Answer

potential difference = current × resistance OR V = I × R (Accept standard algebraic rearrangements like R = V / I or I = V / R ).

💡 Key Knowledge

Ohm's Law / circuit equation: Potential difference ($V$) across a component is directly proportional to the current ($I$) flowing through it, provided temperature remains constant (though filament lamp resistance changes as it heats up).

🧠 Exam Technique

Write standard accepted symbols or full words. Avoid informal shorthand like "volts equals amps times ohms".

Mark breakdown: 1 mark for correctly stating the equation.

Question 01.4

Calculating Resistance from Graph Data (4 Marks)

📐 Calculation Steps

Find current: Locate 1.0 V on the x-axis of Figure 2, go up to the curve, and read across to find the current I = 0.08 A .
Recall formula: R = V / I
Substitute values: R = 1.0 / 0.08
Calculate final answer: R = 12.5 Ω

🧠 Exam Technique

Use a sharp pencil and ruler to read values accurately off graph axes. Double-check small grid square values (here, each small square on the current axis represents 0.005 A ).

❌ Common Calculation Traps

Misreading scale values (e.g., reading 0.08 as 0.8) is the most common reason students lose marks here. Ensure units are consistent.

Mark breakdown: 1 mark for reading correct current from graph (0.08 A), 1 mark for substituting into equation, 1 mark for correct rearrangement/calculation, 1 mark for final unit/answer (12.5 ohms).

Question 01.5

Defining Zero Error (1 Mark)

✅ Correct Answer

An ammeter displaying a reading when not connected to a circuit (when the true value should be zero).

💡 Key Knowledge

A zero error is a type of systematic error caused by equipment giving a non-zero reading when there is no input (e.g., a digital scale showing 0.05 g before anything is placed on it).

🧠 Exam Technique

Keep definitions precise and concise. Mentioning "false reading when switched off or disconnected" secures the mark instantly.

Mark breakdown: 1 mark for identifying that the meter gives a reading when unattached or when current is zero.

Topics

Physics · Required Practicals · P2: Electricity · Required Practicals

Question and mark scheme from the AQA GCSE Physics examination, Physics Paper 1 (Higher), November 2020. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.