Question 1 of Paper 5 asks for a labelled diagram of an experiment you may never have built. Here the experiment is measuring the magnetic flux density B along the axis of a flat coil with a Hall probe. Watch it built step by step, then build it yourself on the bench and check it against the mark points. Every step says what the Cambridge examiner reports found students getting wrong.
Past-paper referenceOriginal experiment, wording and figures, written in the style of Cambridge AS & A Level Physics 9702 Paper 5, Question 1. It is not copied from a past paper. The “what the examiners said” notes are our paraphrase of the Principal Examiner Reports for Teachers.
Practise next: 9702/52 May/June 2014, Question 1 (Hall probe between two parallel coils) · official past papers
Practise next: 9702/52 October/November 2016, Question 1 (Hall probe above an electromagnet) · official past papers
Examiner reports used: 9702 June 2014, November 2016, March 2023, June 2023 and March 2024.
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What a full-mark diagram shows
The coil circuit
A d.c. supply, an ammeter and a rheostat in series with the coil, drawn with correct circuit symbols. Nothing else in series.
The Hall probe
The sensor exactly where B is wanted, its face at right angles to the field, and its own voltmeter or c.r.o. in a separate circuit.
The independent variable
How x is measured: a metre rule shown in position and supported, with clear start and end points.
Labels
Label the important apparatus. An unlabelled sketch does not earn the diagram mark.
Habits the examiner reports keep asking for
Say “kept constant”, not “controlled”, and name each quantity with the symbol used in the question.
Describe how you measure, not just the equation you will use.
Never just “repeat and average”. Say what is repeated for each value and what is averaged.
Write “the relationship is valid if the graph is a straight line” and only add “through the origin” when the equation says so.
Imagine doing it in the lab. The reports say students with hands-on practice score far more of the detail marks.