Practical Terms Flashcards
(29 cards)
Logarithmic scale
A scale such that equal intervals correspond to a change by a constant factor
Accuracy
The closeness of a measurement to the true value
Error bar
Representation of an uncertainty on a graph
Independent variable
Physical quantities whose values are selected or controlled by the experimenter
Zero error
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
Reproducible
An experiment or measurement that gives the same results when it is repeated by another person or by using different equipment/techniques
Systematic errors
Cause readings to differ from the true value by a consistent amount each time a measurement is made.
Accepted value
Value of the most accurate measurement available. Sometimes called ‘true value’
Random errors
Cause readings to be spread about the true value, due to the results varying in an unpredictable way from one result to the next
Dependent variable
The variable of which the value is measured for each and every change in the independent variable
Radian
1 radian = 360/(2pi) degrees
SI system
The scientific system of units
Linearity
An instrument that gives readings that are directly proportional to the magnitude of the quantity being measured
Valid measurement
Measurements that give the required information by an acceptable method
Sensitivity of an instrument
Output response per unit input quantity
Repeatable
An experiment or measurement that gives the same results when it is repeated by the original experimenter using the same method and equipment
Mean value of a set of readings
Sum of the readings divided by the number of readings
Percentage uncertainty
(Uncertainty/Mean Value)x100%
Precision of a measurement
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
Precision of an instrument
The smallest non-zero reading that can be measured using the instrument, also referred to as the instrument sensitivity or resolution
Range of a set of readings
The maximum and minimum values of a set of readings
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
Uncertainty of a measurement
The interval within which the true value can be expected to lie, with a given level of confidence or probability
Range of an instrument
The minimum and the maximum reading that can be obtained using the instrument.
