A2 Physics EMPA Practical Terms Flashcards
Accepted value
The value of the most accurate measurement available, sometimes referred to as the true value.
Accuracy
Measure of confidence in a measurement, often expressed as the uncertainty or probable error of the measurement.
Random error
Errors which vary randomly with no recognisable pattern or trend or bias.
Systematic error
Errors which show a pattern or trend or bias
Dependent variable
A physical quantity whose value depends on the value of another physical variable.
Independent variable
Physical quantities whose values are selected or controlled by the experimenter
Linearity
Property of an instrument that gives reading that are directly proportional to the magnitude of the quantity being measured.
Mean value of a set of readings
Sum of the readings divided by the number of readings
Percentage uncertainty
= uncertainty / mean value x 100%
Precision of a measurement
The degree of exactness of a measurement, usually expressed as the uncertainty of the readings used to obtain the measurement.
Precision of an instrument
The smallest non-zero reading that can be measured using the instrument.
Range of a set of readings
The difference between the largest and the smallest reading
Reliability
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.
Sensitivity of an instrument
Output response per unit input quantity
Uncertainty of a measurement
Half the range of the readings used to obtain the measurement
