Physics_Practical_Notes (1)

PURE PHYSICS 2020 “O” LEVEL REVISION NOTES Prepared By: Aqil Ahamed Name: _____________________ ( ) Class: 4E2 NOTES PRACTICAL NOTES RECORDING OF DATA Addition, Subtraction, Multiplication and Division of Quantities When doing addition or subtraction of two quantities, express the final answer in the lower of the two decimal points (d.p.) Example: ➢ 60.32 cm – 45.0 cm = 15.3 cm (1 d.p.) ➢ 329.421 m + 67.34 m = 396.76 m (2 d.p.) When doing multiplication or division of two quantities, express the final answer in the lower of the two significant figures (s.f.) Example: ➢ 19.8 m x 0.32 m = 6.3 m2 (2 s.f.) ➢ 20.3 m ÷ 12.52 s = 1.62 ms-1 (3 s.f.) This rule only applies if addition, subtraction, multiplication or division is done with the obtained data. It does not apply when doing calculation with the data and a constant (e.g. 20 oscillations). This is because the constant is infinitely precise. Just follow the number of the decimal points or significant figures from the data. Precision of Apparatus Take the smallest division in the apparatus and divide it by two to obtain the degree of accuracy of the apparatus (if spacing between the divisions are big).

Common Apparatus Used: Apparatus Degree of Accuracy Metre Rule 0.1 cm or 0.001 m Vernier Calipers 0.01 cm Micrometer Screw Gauge 0.01 mm Electronic Stopwatch 0.01 s Analogue Stopwatch 0.1 s Electronic Balance 0.1 g Spring Balance 0.05 N Thermometer 0.5 °C Measuring Cylinder 0.5 cm3 Protractor 1° Ammeter (0 – 1 A) 0.01 A Voltmeter (0 – 5 V) 0.05 V PRESENTATION OF DATA • Table of clear headings/unit. • At least 5 sets of data, unless otherwise stated. • Consistency – Measured Data – follow precision (decimal places) of instrument, unless otherwise stated. • Consistency – Processed Data – follow rules stated under Recording of Data. GRAPH S – Scale (use appropriate scale) such that the graph covers at least half (preferably 75%) of the graph paper. Label the graph at every 2 cm (1 big square). L – Line/Curve that is best fit. A – Axes labelled with quantity/unit. P – Points plotted with small crosses. Join with best fit line or curve. CALCULATION To find gradient from straight line graph. • Identify 2 points far apart on the straight-line graph. Write down the coordinates on the graph. • Draw big dotted triangle. • Show working to calculate gradient. Give your answer according to the rules stated under Recording of Data.

Answering questions that requires to state the relationship between the two quantities in the graph, • y is linearly related to x with a positive gradient. (If line passes through the origin, permissible to say, y and x are directly proportional). • When x increases, y