A good Graph

PROPERTIES OF A GOOD GRAPH (for 5116)

Materials Required
1. Use a soft sharp Pencil for plotting of graph. .

2. Use a transparent 30 cm long ruler to best fit line.

Tables and data
3. The heading of each column should already have the units. Example: L/cm. Do not write the units again in the data within the column.Scale & Axes
4. Choose scale that is easy to plot and easy to read. For example : 2,4,5,10 squares rep. 1N. Do not choose weird (inconvenient) scales like 3,7,9 squares rep. 1N.

5. Axes should be labeled with units. Example : L/cm ; M/g

6. A small graph, squeezed into one corner of the graph paper is unacceptable! The graph should cover as much of the page as possible. Choose a scale that makes the graph big (at least ½ the graph paper)

7. The graph should have a title that tells exactly what relation is being plotted, for example: "Absorbency at 490 nm as a function of FeSCN2- concentration." or “Concentration in moles/L vs Density in grams/mL”.

8. When asked to plot F against L, F is the vertical (Y) axis, L is the horizontal (X) axis.

9. Unless you are asked to determine the Y-intercepts or X-intercepts, there is no need to start the graph from (0,0). Starting the graph from (0,0) usually makes the graph too small.

Plotting and Best-fit Line

10. When the data points are actually plotted they should be represented by a small cross. Do not use a dot.

11. Do not merely attempt to connect all the dots resulting in a zig-zag line. Best fit a straight line (in some rare cases, best fit a curve). Not all points will lie on the line. Try to make your line a true average of all the points by having as many points above the line as below the line. Avoid a bias line.

12. Use a sharp pencil to draw the best fit line. The graph should be a clear sharp single line.

Gradient

13. When determining gradient, show the dotted line of the gradient triangle on the graph. The gradient triangle must be as big as possible. Show the coordinates of the two points used for gradient calculation.

14. Do not use the data points for gradient. Choose two points on the best fit line for gradient calculation.

15. Calculation of gradient should be left as 3 s.f.. Fraction not allowed.


provided by Gui Eng Hong