3.1 Measurements

Question 1

Accurate

Answer 1

• Measurement obtained using calibrated instruments correctly
• Measurement close to the accepted value

Question 2

Accuracy

Answer 2

How close to the true value

Question 3

error bar

Answer 3

uncertainty representation on a graph

Question 4

error of measurement

Answer 4

uncertainty of a measurement

Question 5

precision of measurement

Answer 5

The degree of exactness of the measurement.
The precision is given by the extent of random errors.
Precise readings will have little spread about the mean.

Question 6

precision of instrument

Answer 6

smallest non-zero reading that can be measured - sensitivity or resolution of instrument

Question 7

range of readings

Answer 7

difference of minimum and maximum reading

Question 8

range of instrument

Answer 8

minimum and maximum reading that can be obtained using the instrument

Question 9

systematic error

Answer 9

error of measurement due to readings that constantly differ from the true or mean reading and follow a trend, pattern or bias

Question 10

uncertainty

Answer 10

interval within which the true value can be expected to lie

Question 11

zero error

Answer 11

difference between the reading and zero when the reading should be zero

Question 12

accepted value

Answer 12

value of the most accurate measurement available

Question 13

types of errors

Answer 13

• random error - randomly with no recognisable pattern, trend or bias
• systematic error - differ systematically and show a pattern, trend or bias

Question 14

dependent variable

Answer 14

physical quantity whose value depends on the value of another physical variable

Question 15

mean value of a set of readings

Answer 15

sum of the readings divided by the number of readings

Question 16

precision of a measurement

Answer 16

degree of exactness of a measurement - precise measurements have little spread around the mean value

Question 17

precision of an instrument

Answer 17

smallest nonzero reading that can be measured using an instrument - sometimes called sensitivity or resolution

Question 18

range of set of readings

Answer 18

difference between the minimum and maximum readings

Question 19

range of an instrument

Answer 19

maximum and minimum values that can be obtained using an instrument

Question 20

reliability

Answer 20

if a consistent value is obtained

Question 21

random error

Answer 21

error of measurement due to readings that vary randomly with no recognisable pattern, trend or bias

Question 22

Base units

Answer 22

Units that define the SI system: Kg, Amp, s, m

Question 23

independent variable

Answer 23

physical quantities whose values are selected or controlled by the experimenter

Question 24

linearity

Answer 24

instrument that gives readings that are directly proportional to the magnitude of the quantity being measured