3.1.2 - Uncertainty

Question 1

Absolute uncertainty =

Answer 1

Resolution / 2

Question 2

Fractional uncertainty =

Answer 2

Absolute uncertainty / measured value

Question 3

Percentage uncertainty =

Answer 3

Absolute uncertainty / measured value x100

Question 4

What do you do with the uncertainty when you add or subtract values?

Answer 4

Add the absolute uncertainties.

Question 5

What do you do with uncertainty when multiplying values?

Answer 5

Add the percentage uncertainties.

Question 6

What do you do with uncertainty when you divide values?

Answer 6

Add the percentage uncertainties.

Question 7

If there are powers in the equation what do you do with uncertainty?

Answer 7

Multiply the percentage uncertainty by the power.

Question 8

How do you estimate the uncertainty in the mean?

Answer 8

Range / 2

Question 9

In what case should you ignore an anomalous result?

Answer 9

If it had a reason which could be identified it can be ignored.

Question 10

When plotting what should you do with anomalous results?

Answer 10

Plot them but ignore them when the line of best fit is being decided.

Question 11

When else should anomalous results be ignored?

Answer 11

When the results are expected to be the same.

Question 12

When should anomalous results be included?

Answer 12

When there is no obvious error or expectation that the results should be the same.

Question 13

On graphs how do you work out percentage uncertainty?

Answer 13

( (best gradient - worst gradient) / best gradient) x100

Question 14

How else can you work out percentage uncertainty on a graph?

Answer 14

( (best y intercept - worst y intercept) / best y intercept) x 100

Question 15

Why do we use error bars?

Answer 15

To indicate the maximum error and minimum error we could get.