EJC Physics 2324 Physics Practical Guide

General Information Examination Physics practical skills are tested in Paper 4, a 2 h 30 min paper that makes up 20% of the overall A-Level score in H2 Physics. Total marks of the paper is 55 marks. In the first 2  1 hr, candidates take turns to attempt either 1 long experiment or 2 short experiments. Candidates will then swap work benches to finish the practical components. In the last 30 min, candidates will attempt a question which tests their ability to plan for an experiment – they will not be allowed to work with any apparatus then. Experimental skills and investigations Candidates should be able to: 1. follow a detailed set or sequence of instructions and use techniques, apparatus and materials safely and effectively 2. make, record and present observations and measurements with due regard for precision and accuracy 3. interpret and evaluate observations and experimental data 4. identify a problem, design and plan investigations 5. evaluate methods and techniques, and suggest possible improvements. Overview of Question Types The range of questions include • single measurements: show repeated measurements. • setup: be careful of the relative positioning of equipment. • table of measurements: you’d likely need to check forward for the equation to better guide your lay-out for optimal presentation. • equation relating the measured quantities: check to see if a straight line (linear) graph is expected or a curve. • graph: plot the graph using the guidelines. • interpretation of the graph data: you should never use the raw data points in your table. Rather, you need to read off the best-fit line to an accuracy of half-smallest-square. • further questions: may look further into uncertainties, improvements and meaning behind quantities.

1. Precision of Laboratory Instruments Example The precision of the laboratory equipment contributes to the uncertainty in measurement. The number of decimal places for raw data must be consistent as it will reflect the precision of the instrument. For digital instruments, record the full value that is provided on the screen. For non-digital instrument (ruler, thermometer…) , record to the precision of the instrument. A non -exhaustive list of apparatus and their precisions is provided below. For vast majority of instruments, precision = smallest division available. There are a few exceptions. It will be to your benefit to understand the principles behind their precision rather than memorise them. No Apparatus Smallest Division Precision of instrument Examples of recording 1 Ammeter (0 - 1 A) 0.02 A 0.01 A 0.20 A, 0.21 A 2 Milliammeter (0 - 100 mA) 2 mA 1 mA 20 mA, 21 mA 3 Voltmeter (0 - 5 V) 0.1 V 0.05 V 2.50 V, 2.55 V 4 Digital multimeter (DMM) Record what is displayed on DMM. 5 Half metre rule or metre rule 0.1 cm 0.1 cm 0.8 cm, 12.1 cm 6 Vernier calipers 0.01 cm 0.01 cm 0.22 cm, 7.51 cm 7 Micrometer 0.01