2.1: Physical Quantities and Units - Part 2

Question 1

How can systematic error be reduced?

Answer 1

Calibrate apparatus before using e.g. setting a mass balance to zero before use.

Question 2

What is precision?

Answer 2

How consistent/close repeat readings are together. The closer they are, the more precise they are.

Question 3

What makes an experiment repeatable?

Answer 3

If the original experimenter can be complete the experiment again with the same method and equipment and achieve the same results.

Question 4

What makes an experiment reproducible?

Answer 4

If the experiment can be redone by a different person or with different techniques and equipment and produce the same results.

Question 5

What is resolution?

Answer 5

The smallest change in the quantity being measured that gives a recognisable change in reading.

E.g. On a ruler, the resolution is 1mm.

Question 6

What is absolute uncertainty?

Answer 6

Uncertainty given as an exact value.

E.g. 7 +/- 0.6 V

Uncertainty should be the same number of significant figures as the data.

Question 7

What is the percentage uncertainty in 7 +/- 0.6 V

Answer 7

(0.6/7) x 100 = 8.571%

                   = 8.6% (2 s.f.)

Question 8

What is the fractional uncertainty of 7 +/- 0.6 V?

Answer 8

0.6/7

Question 9

How can percentage and fractional uncertainty be reduced?

Answer 9

Measure larger quantities.

E.g. Measure a longer distance if your experiment takes distance into account.

Question 10

What is the difference between a reading and a measurement?

Answer 10

Readings are when one value is found. Measurements are when the difference between two readings are found.