Plotting Graphs

A well-drawn graph makes patterns clear and lets you find gradients and intercepts accurately. Examiners check the following.Axes: plot the independent variable (the one you change) on the x-axis and the dependent variable (the one you measure) on the y-axis. Label each axis with the quantity and its unit, separated by a solidus, for example t / s or V / V.Scales: choose linear scales that are easy to read, using 1, 2 or 5 units (or multiples of ten of these) per large square. Avoid awkward scales such as 3 or 7 per square. The plotted points should cover at least half of the grid in each direction. The origin does not have to be included unless you need the intercept.Points: plot points accurately (to within half a small square) as small, neat crosses.Line of best fit: draw a single thin straight line or smooth curve, not dot-to-dot. It should have roughly equal numbers of points on each side of it. Do not force the line through the origin, and ignore anomalous points when placing it.Tables: give each column a heading with the quantity and unit, and record values in a column to the same number of decimal places.Worked example: The y values go up to 7.3 V and the grid is 8 large squares tall. A scale of 1 V per large square uses about 7.3 of the 8 squares, over half the grid, and is easy to read. A scale of 2 V per square would use less than half, so it is not suitable.