Cambridge International AS & A Level · 20 · structured
Design, predict and evaluate an induction test
An induction experiment with controlled comparisons · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- demanding
- Marks
- 12
- Topics
- 1
- Answer
- Complete
Plan an experiment demonstrating that changing flux induces an e.m.f., testing its direction and how its magnitude depends on speed. Include apparatus, a stationary control, controlled variables, speed and voltage readings, repeats and uncertainty. Predict what happens when a north pole approaches, stops and withdraws. Explain how turn number could be tested without confusing e.m.f. with resistance-dependent current.
- (a)
Describe a workable apparatus and the stationary/approach/withdrawal direction test.
4 marks - (b)
Plan controlled speed measurements and uncertainty-aware analysis.
5 marks - (c)
Explain the turns comparison and one safety/measurement refinement.
3 marks
Ready to self-mark?Reveal the detailed answer guide
(a)
Describe a workable apparatus and the stationary/approach/withdrawal direction test.
Identify what the question is testing, organise the response into distinct mark-earning points, and make every conclusion traceable to a physical principle or to the evidence supplied.
- 1
Connected fixed coil and axial magnet, labelled polarity, stationary zero, N approach gives near-face N and withdrawal near-face S.
(b)
Plan controlled speed measurements and uncertainty-aware analysis.
Identify what the question is testing, organise the response into distinct mark-earning points, and make every conclusion traceable to a physical principle or to the evidence supplied.
- 1
Measured speed, resolved voltage, fixed geometry/electrics, repeats, uncertainty treatment and graph/conclusion.
(c)
Explain the turns comparison and one safety/measurement refinement.
Identify what the question is testing, organise the response into distinct mark-earning points, and make every conclusion traceable to a physical principle or to the evidence supplied.
- 1
Same geometry and motion; high-input-resistance voltage measurement to avoid resistance confounding; relevant safe or resolving setup.
Complete marking guidance
Use these worked steps alongside the part-by-part answers. They explain the method and mark allocation; they do not add extra marks.
- Describe an assembled fixed coil, axial magnet guide, voltage logger/centre-zero meter and speed-measurement method.
- Record a stationary baseline; approach, stop and withdraw with fixed lead connections. No change gives zero sustained e.m.f.
- For north approach the near coil face is north, opposing the increase; for withdrawal it is south, opposing the decrease. The polarities reverse.
- Vary measured speed while keeping magnet, path, alignment, coil, endpoints and electrical connections fixed.
- Record resolved peak e.m.f. traces, repeat each setting and include speed uncertainty, voltage resolution, sample timing and scatter.
- Compare mean peaks with uncertainty bars over several speeds; discuss whether the difference and any proportionality are supported.
- For turns, keep coil geometry and flux change equivalent, and measure voltage with input resistance much greater than coil resistance.
- State a relevant safety precaution and limitation, such as secured magnets and short-pulse sampling.
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