Module 2 Fundamental data analysis

Question 1

How can you identify that a graph is a log graph? What is the base of the log?

Answer 1

Each increment on the axis represents an equal factor, e.g. every gridline could represent a x10 increase. The factor is known as the base of the log?

Question 2

What two types or errors are uncertainties caused by?

Answer 2

Random and systematic

Question 3

Describe the systematic errors

Answer 3

Include zero errors
They are the same every time you repeat the experiment, they shift all the values by the same amount. They may be caused by the equipment you’re using or how it’s set up. Systematic errors are really hard to spot, and they affect the accuracy of your results.

Question 4

Describe random errors. How can you reduce their effect?

Answer 4

They vary – they’re what make the results a bit different each time you repeat an experiment. It could be that you just can’t keep controlled variables exactly the same throughout the experiment. Using equipment with a higher resolution means that the equipment can detect smaller changes. This can reduce random error and so your results can be more precise. Repeating measurements can also reduce the effects of random errors

Question 5

Describe what you do with the uncertainties, if you are adding or subtracting data

Answer 5

And the absolute uncertainties

Question 6

Describe what you do to the uncertainties, if you are multiplying or dividing data

Answer 6

You add the percentage uncertainties

Question 7

Describe what you do to the uncertainty, when you raise a datum to a power

Answer 7

Multiply the percentage uncertainty by the power

Question 8

How do you find the uncertainty in the value of the gradient of a graph?

Answer 8

Use worst lines.
Draw lines of best fit which have the maximum and minimum possible slopes for the data and which should go through all the uncertainty bars. These are the worst lines for your data. Calculate the worst gradient – the gradient of the slope that is furthest from the gradient of the line of best fit. The uncertainty in the gradient is given by the difference between the best gradient and the worst gradient.

Question 9

How do you find the uncertainty in the y-intercept of a graph?

Answer 9

Draw the worst lines through the uncertainty bars. The uncertainty is the difference between the best and worst intercepts