Practical Terms

Question 1

Logarithmic scale

Answer 1

A scale such that equal intervals correspond to a change by a constant factor

Question 2

Accuracy

Answer 2

The closeness of a measurement to the true value

Question 3

Error bar

Answer 3

Representation of an uncertainty on a graph

Question 4

Independent variable

Answer 4

Physical quantities whose values are selected or controlled by the experimenter

Question 5

Zero error

Answer 5

Any indication that a measuring system gives a false reading when the true value of a measured quantity is zero. A zero error may result in a systematic uncertainty

Question 6

Reproducible

Answer 6

An experiment or measurement that gives the same results when it is repeated by another person or by using different equipment/techniques

Question 7

Systematic errors

Answer 7

Cause readings to differ from the true value by a consistent amount each time a measurement is made.

Question 8

Accepted value

Answer 8

Value of the most accurate measurement available. Sometimes called ‘true value’

Question 9

Random errors

Answer 9

Cause readings to be spread about the true value, due to the results varying in an unpredictable way from one result to the next

Question 10

Dependent variable

Answer 10

The variable of which the value is measured for each and every change in the independent variable

Question 11

Radian

Answer 11

1 radian = 360/(2pi) degrees

Question 12

SI system

Answer 12

The scientific system of units

Question 13

Linearity

Answer 13

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

Question 14

Valid measurement

Answer 14

Measurements that give the required information by an acceptable method

Question 15

Sensitivity of an instrument

Answer 15

Output response per unit input quantity

Question 16

Repeatable

Answer 16

An experiment or measurement that gives the same results when it is repeated by the original experimenter using the same method and equipment

Question 17

Mean value of a set of readings

Answer 17

Sum of the readings divided by the number of readings

Question 18

Percentage uncertainty

Answer 18

(Uncertainty/Mean Value)x100%

Question 19

Precision of a measurement

Answer 19

Precise measurements are ones in which there is very little spread about the mean value. Precision depends only on the extent of random error and gives no indication of how close the results are to the true value

Question 20

Precision of an instrument

Answer 20

The smallest non-zero reading that can be measured using the instrument, also referred to as the instrument sensitivity or resolution

Question 21

Range of a set of readings

Answer 21

The maximum and minimum values of a set of readings

Question 22

Reliability

Answer 22

An experiment or measurement is reliable if a consistent value is obtained each time it is repeated under identical conditions. The reliability of an experiment is increased if random and systematic errors have been considered and eliminated and, where appropriate, a more precise best fit line has been obtained

Question 23

Uncertainty of a measurement

Answer 23

The interval within which the true value can be expected to lie, with a given level of confidence or probability

Question 24

Range of an instrument

Answer 24

The minimum and the maximum reading that can be obtained using the instrument.

Question 25

Why is it important to test by experiment the prediction of a scientific theory

Answer 25

If a reliable experiment does not support a hypothesis, the hypothesis must be changed

Question 26

Explain what must happen in order for an existing scientific theory to be modified or replaced with a new theory

Answer 26

The predictions of the theory must be tested by repeatable experiments checked by other scientists (peer reviewed)

Question 27

What must be done to validate the predictions of an unconfirmed scientific theory.

Answer 27

The hypothesis must be tested by experiment, this experiment must be repeatable

Question 28

Describe how would you use an oscilliscope to display an alternating waveform

Answer 28

Connect to y-input, adjust time base

Question 29

Why is it important to test by experiment the prediction of a scientific theory

Answer 29

If a reliable experiment does not support the hypothesis the hypothesis must be rejected