AQA A-level Physics 7408/3 - Paper 3
Prediction (2025)
Instructions
Time allowed: 2 hours
Materials:
- Ruler
- Scientific calculator
- Protractor (optional)
Instructions:
- Use black ink or ballpoint pen.
- Answer all questions.
- You must show all your working.
- Do all rough work in this answer book. Cross through any work you do not want to be
marked.
Information:
- The marks for questions are shown in brackets.
- The maximum mark for this paper is 80.
Section A: Practical Skills and Data Analysis
1. Measuring resistivity of a wire (8 marks)
(a) Describe the procedure the student should follow to determine the resistivity, including
how they would minimize uncertainties. (5 marks)
Ans. The student should take the reading of the current and voltage using the voltmeter and
ammeter near the wire. Find the length of the wire to reduce error use a cm ruler and use
vernier caliper to find the diameter to reduce error take 3 reading from different positions
of the wire and find the area of the wire. Plot a graph against V and I and take a gradient of
the graph and use the formula R = rho L/A.
(b) The student obtains a gradient of 2.00 Ohm/m from a resistance vs. length graph. The
diameter of the wire is measured as (0.30 ± 0.01) mm.
Calculate the resistivity, including percentage uncertainty. (3 marks)
Ans. 2± 0.02 Ohm/m
Prediction (2025)
Instructions
Time allowed: 2 hours
Materials:
- Ruler
- Scientific calculator
- Protractor (optional)
Instructions:
- Use black ink or ballpoint pen.
- Answer all questions.
- You must show all your working.
- Do all rough work in this answer book. Cross through any work you do not want to be
marked.
Information:
- The marks for questions are shown in brackets.
- The maximum mark for this paper is 80.
Section A: Practical Skills and Data Analysis
1. Measuring resistivity of a wire (8 marks)
(a) Describe the procedure the student should follow to determine the resistivity, including
how they would minimize uncertainties. (5 marks)
Ans. The student should take the reading of the current and voltage using the voltmeter and
ammeter near the wire. Find the length of the wire to reduce error use a cm ruler and use
vernier caliper to find the diameter to reduce error take 3 reading from different positions
of the wire and find the area of the wire. Plot a graph against V and I and take a gradient of
the graph and use the formula R = rho L/A.
(b) The student obtains a gradient of 2.00 Ohm/m from a resistance vs. length graph. The
diameter of the wire is measured as (0.30 ± 0.01) mm.
Calculate the resistivity, including percentage uncertainty. (3 marks)
Ans. 2± 0.02 Ohm/m
