Physics practical notes

1. Refer to diagrams whenever you want to - set up - make measurements - identify sources of error - also look for any difficulty in obtaining the measurements 2. Read THOROUGHLY — highlight important phrases. Pay attention to diagrams. 3. Ensure that all answer spaces are completed. 4. DO NOT spend more than 20 mins collecting data, so that you will have enough time to spend when processing the data. 5. Use a sharp and dark pencil for graph and diagrams. 6. Raw data are to be written to the correct number of decimal places according to the instrument’s precision. (ALL calculated values must be 3 s.f.) 7. Ratio / Fractions should be calculated as a decimal number, to 3 s.f. 8. For graphs, - Axes: must be labelled as quantity/unit (example: x/cm, T/s,m/g) - Scale: large!! Spacing between first point and last point must be more than half the graph page ( horizontally and vertically ) - Have a sensible ratio for your scale, e.g. 1cm represent 1, 2 units General precautions and sources of error: Type of experiment: Precautions: Sources of error: Pendulum - Use small angle for swinging - Pendulum oscillates along the vertical plane, no wobbling - Human reaction error is incurred when measuring the time - Extended string -> affects the length - Wobbled swing -> affects the time Balancing - Ensure that the metre rule is balanced horizontally by measuring the height at each end using another metre rule to be equal - Centre-of-mass of ruler may not be at the centre -> affects the distance Spring - To ensure that a metre rule is vertical, place a set square against the rule and the bench top or align the metre rule with a vertical feature such as the frame of a door - The pointer of the spring must touch the scale of the - The spring did not oscillate vertically -> affects the time

metre rule Mirror / Glass block - Place the pins vertically - Pins are sufficiently far apart ( at least 5cm ) - Mark with a ‘x’ on the holes - Place one eye at the same level as the pins when viewing - Place the reflecting surface of the mirror on the line Thickness of mirror -> affects the reflection -> affects the measured angle Mirror is light -> It moves easily -> affects position of mirror when placed on the line ( inconsistent ) -> affects the measured angle Pins has thickness -> holes made are larger -> affects the drawing of rays The bevel edge of the glass block -> affects the glass block’s positon when placed on the drawn outline ( inconsistent ) Lens - Stick the mtre rule to the bench using p