1.0 Measurements And Their Errors

Question 1

Define random errors

Answer 1

Unpredictable deviations in the result from the true value

Question 2

Define systematic errors

Answer 2

Constant deviations from true results due to flaws in experimental methods, instrument calibration, or environmental conditions.

Question 3

Define zero errors

Answer 3

A type of systematic error where a reading is given when the true reading should be zero

Question 4

Define precision

Answer 4

Degree of exactness or consistency in repeat readings

Question 5

Define repeatability

Answer 5

The ability to produce consistent results when repeated

Question 6

Define reproducibility

Answer 6

the ability to obtain the same results when with different equipment, different techniques or completed by another person

Question 7

Define resolution

Answer 7

The smallest change in a measured quantity that an instrument can detect or display

Question 8

Define accuracy

Answer 8

How close a result is to the true value

Question 9

Define uncertainty

Answer 9

The measure of how confident you can be in a measurement

Question 10

Absolute uncertainty

Answer 10

uncertainty given as a fixed quantity
e.g. 100 cm ± 1 cm

Question 11

Fractional uncertainty

Answer 11

uncertainty given as a fraction of the measurement

Question 12

Percentage uncertainty

Answer 12

uncertainty given as a percentage of the measurement

Question 13

Uncertainty in a reading

Answer 13

± half the smallest division

Question 14

Uncertainty in a measurement

Answer 14

at least ±1 smallest division

Question 15

Uncertainty in repeated data

Answer 15

± half the range

Question 16

The uncertainty in digital readings

Answer 16

± the last significant digit unless otherwise quoted

Question 17

Adding or subtracting data with uncertainties

Answer 17

add absolute uncertainties

Question 18

Multiplying or dividing data with uncertainties

Answer 18

add fractional or percentage uncertainties

Question 19

Raising data with uncertainties to a power

Answer 19

multiply the percentage uncertainty by the power

Question 20

How to measure uncertainty on graphs

Answer 20

Use error bars

Question 21

Directions of error bars

Answer 21

vertical - uncertainty in y
horizontal - uncertainty in x

Question 22

Error bar values

Answer 22

Shows the absolute uncertainty

Question 23

Best gradient in graph uncertainties

Answer 23

best line that passes as close to the points as possible

Question 24

Worst gradient in graph uncertainties

Answer 24

either the steepest possible or the shallowest possible line which fits within all the error bars

Question 25

Percentage uncertainty in the gradient

Answer 25

=(best - worst)÷best × 100

Question 26

Percentage uncertainty in the y-intercept

Answer 26

=(best - worst)÷best × 100

Question 27

Orders of magnitude

Answer 27

Scale of a value expressed as an order of 10

Question 28

Speed of sound in air

Answer 28

300m/s

Question 29

Atmospheric pressure

Answer 29

1×10⁵Pa