All exerimental data is subject to uncertainty caused by error margins in apparatus, operation and design. This section looks at how the errors and uncertainties are recorded and propagated through a calculation.
Essential idea: Graphs are a visual representation of trends in data.
Graphical techniques are an effective means of communicating the effect of an independent variable on a dependent variable, and can lead to determination of physical quantities.
Sketched graphs have labelled but unscaled axes, and are used to show qualitative trends, such as variables that are proportional or inversely proportional.
Drawn graphs have labelled and scaled axes, and are used in quantitative measurements.
Applications and skills
Drawing graphs of experimental results including the correct choice of axes and scale.
Interpretation of graphs in terms of the relationships of dependent and independent variables.
Production and interpretation of best-fit lines or curves through data points, including an assessment of when it can and cannot be considered as a linear function.
Calculation of quantities from graphs by measuring slope (gradient) and intercept, including appropriate units.