Practical Guide
Drawing Graphs
- Scales for axes should allow majority of the graph paper to be used
- Graph needs NOT start from origin, but starting values for x and y axes must be labelled
- Each data point should be plotted to an accuracy better than one half of one of the smallest squares on the grid
- Equal number of points on either side of the line when a straight line is required
- Gradient should be taken by using a triangle with a hypotenuse that extends over at least half the length of the line
- Calculation of the gradient should be to two or three significant figures
- Label coordinates of points used to find gradient
Precision of Instruments
| Appartus | Smallest Division | Uncertaincy | Examples |
|---|---|---|---|
| Burette | 0.1cm^3 | 0.05cm^3 | 10.00cm^3, 10.05cm^3 |
| Electronic balance | 0.1g | 0.1g | 150.0g, 151.1g |
| Ruler | 0.1cm | 0.1cm | 11.1cm. 11.0cm |
| Stopwatch | 0.1s | 0.01s | 28.1s |
| Ammeter | 0.02A | 0.01A | 0.10A, 0.11A |
| Miliammeter | 2mA | 1mA | 10mA, 11mA |
| Voltmeter | 0.1V | 0.05V | 1.50V, 1.55V |
| Spring balance | 0.1N | 0.05N | 5.65N, 5.70N |
| Protractor | 1\degree | 1\degree | 26\degree |
SF DP rule
- For addition or subtraction, the answer will follow the variable with the least decimal place
- For multiplication or division, the answer will follow the variable with the least significant figure
Measurement
- Find the zero error +/-
- Measure 3 readings
- Find the average reading
- Correct zero error (average reading - zero error)
Planning
- Independent variable
- Dependent variable
- Key constants (3)
- Procedure:
- Apparatus used
- Formula for any calculations
- 1st repetition for average
- 2nd repetition to obtain different sets of values
- Not needed to plot graph. Just stating x and y axes is sufficient
- Draw table. Must include raw data and calculated data(average)
21:56 Sunday 02 October 2022