AQA A-Level Physics – Paper 2: Fields, Nuclear Physics, and Electricity

AQA
A-Level Physics – Paper 2: Fields, Nuclear Physics, and Electricity

Mark Scheme – Monday 09 june 2025
Time allowed: 2 hours



Section A – Context Questions

Answer EITHER Context 1 OR Context 2



Context 1: Electric Fields around a Point Charge

1(a) Factor by which electric field changes from 0.1 m to 0.2 m

Factor = E1/E2 = 900/225 = 0.25
 Electric field reduces to 1/4 when distance doubles (inverse-square law).
Marks: 3

 1 mark: correct identification of values

 2 marks: correct calculation / factor

1(b) Define electric field strength

 Electric field strength at a point is the force per unit positive charge experienced at that point.
Marks: 2

1(c) Reason electric field weaker at greater distances

 Force reduces with distance according to inverse-square law:




 Fewer field lines per unit area → weaker field
Marks: 4 (1 for identification, 3 for explanation)

1(d) Analyse effect of doubling point charge



 Force on test charge



 Doubling Q doubles force at all points (linear relationship)

,  Could include diagram showing proportional increase
Marks: 9 (3 knowledge, 3 analysis, 3 application/diagram)

1(e) Evaluate field lines

 Pros: visual representation, direction, magnitude indication

 Cons: qualitative only, spacing not exact, 3D fields difficult to represent

 Judgement: useful for understanding but not for quantitative calculations
Marks: 17 (4 knowledge, 4 analysis, 9 evaluation + judgement)



Context 2: Radioactive Decay

2(a) Define half-life

 Half-life is the time taken for half the nuclei in a radioactive sample to decay.
Marks: 2

2(b) Explain pattern of activity

 Activity halves every 4 hours → exponential decay

 Activity decreases over time but never reaches zero

 Could include diagram / decay curve
Marks: 4 (2 knowledge, 2 application)

2(c) Implications for radioactive waste

 Storage time must be several half-lives

 Safety precautions to reduce radiation exposure

 Shielding and secure containment required
Marks: 9 (3 identification, 3 explanation, 3 real-world application)

2(d) Evaluate medical isotopes

 Benefits: diagnosis (tracers), treatment (radiotherapy), sterilisation

 Risks: radiation exposure, contamination, disposal issues

 Judgement: benefits often outweigh risks if safety protocols followed
Marks: 17



Section B – Extended Response Essays

Essay 1: Gravitational and Electric Fields

Marking Guidance – 40 marks