2.1 Graphical Treatment Of Errors And Uncertainties

Question 1

What is percentage difference?

Answer 1

• the difference between two values divided by the average and shown as a percentage

Question 2

What are error bars?

Answer 2

• represent the absolute uncertainty in measurements and can be plotted in the x and y directions

Question 3

What isa worst fit line?

Answer 3

• the worst acceptable line still passing through all the error bars. This will be either the steepest possible line of fit or th least steep line of fit.

Question 4

How do you work out the uncertainty in a gradient?

Answer 4

• add error bars to each point
• draw line of best fit through scattered points and error bars
• calculate gradient of best fit
• do same for worst line of fit
• work out difference between best and worst
• uncertainty = gradient best - gradient worst
• PU = (uncertainty/gradient of best fit) x100