The rules of graphing are
Graphs need a Title
Put in the points and draw the graph in pencil — so you can erase mistakes which are all too easy to make.
Use the space available. Do not plot graphs in small spaces; use complete pages. Choose scales that are easy to use and so that the graph occupies most of a page.
Now we must remember which variable to put on which axis, the Independent variable, the one you change, should go along the y-axis and the dependent variable, the one that changes due to the change you made, should go on the x - axis.
You really need to know the relationship between each variable before you can accurately plot its graph. V vs I,
- Count the number of squares you have on your page. (Count the boxes up & across)
- if the x range is greater than the y range of values turn your graph so it has more room
- divide the max value by the number of squares (counted in 1) on the graph in the x and the y,
- round up this number to the next whole number that begins with a 1, 2 or a 5 and only has 0's after this digit. (think about it like money and denominations ... )
- Give these values to the graph axis x and y with each of these values attributed to each box
- Label the axes fully and carefully, with the names of the variables (what is being plotted) and the units.
We need an example here
There is a very useful website with detailed information on drawing graphs at the following url:
The NOT rules of HOW TO GRAPH are here,
as some students always do the opposite of the instruction this maybe the way forward.
How to use the graph to find a value.
The usual key here is to draw a straight line graph going as close to all the points that have been drawn.
After this take 2 points that are on the drawn line, use these points to find the slope of the line.
This is the equivalent of finding the ratio of the y-valued axis over the x-valued axis.
So if the value you require is this .... woila!
Data Grapher thanks to Zona