Foundations Of Physics Flashcards
(40 cards)
What does and “SI” unit mean?
(the international system of units)
The metric system that is used universally as a standard for measurements
What is a derived unit?
A unit of measurement in the international system of units (SI) that is obtained from one or more of the seven base units eg/ volume
Define the term ‘Accuracy’
A measuremet result is considered accurate if it is judged to be close to the true value
Define the term ‘Calibration’
Marking a scale on a measureint instrument. This nvolves establishing the relationship between indications of a measuring insturment and standard or reference quantity values, which must be applied. For example, placing a thermometer in melting ice to see wheather it reads zero, in order to check if it has been calibrated correctly.
Define the term ‘Data’
information, either qualitative or quantitative, that has been collected.
Define the term ‘Errors’
See also uncertainties
Define the term ‘Measurement error’
The difference between a measured value and the true value
Define the term ‘Anomalies’
These are values in a set of results which are judged not to be part of the variation caused by random uncertainty
Define the term ‘Random Error’
These cause reading to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next.
Random errors are present when any measurement is made, and cannot be corrected. The effect of random errors can be reduced by making more measurements and calculating a new mean.
Define the term ‘Systematic Error’
These cause readings to differ from the true value by a consistent amount each time a measurement is made. Sources of systematic error can include the environment, methods of observation or instruments used.
Systematic errors cannot be dealt with by simple repeats. If a systematic error is suspected, the data collection should be repeated using a differnt technique or a differnt set of equipment, and the resukts compared.
Define the ter, ‘Zero Error’
Any indication that a measuring system gives a false reading when the true value of a measured quantity is zero, eg the needle on an ammeter failing to return to zero when no current flows.
A zero error may result in a systematic uncertainty.
Define the term ‘Evidence’
Data which has been shown to be valid
Define the term ‘Valid test’
A fair test is one in which only the independant variable has been allowed to affect the dependent variable.
Define the term ‘Hypothesis’
A propsal intended to explain certain facts or observations
Define the term ‘Interval’
The quantity between readings, eg a set of 11 readings equally spaced over a distance of 1 meter would give an interval of 10 centimetres.
Define the term ‘Precision’
Precise measurements are ones in which there is very little spread about the mean value. Precision depends only on the extent of random errors - it gives no indication of how close results are to the true value.
Define the term ‘Prediction’
A prediction is a statement suggesting what will happen in the future, based on observation, experience or a hypothesis.
Define the term ‘Range’
The maximum and minimum values of the independant or dependant variables; important in ensuring that any pattern is detected.
Define the term ‘Repeatable’
A measurement is repeatable if the original experimenter repeats the investigation using the same method and equipment and obtains the same result.
Define the term ‘Reproducibility’
How closely the same physical quanitity measured by others using differnt techniques and/or measuring instruments agree.
Define the term ‘Resolution’
This is the smallest change in the quantity being measured (input) of a measuring instrument that gives a perceptible change in the reading.
Define the term ‘Sketch graph’
A line graph, not necessarily on a grid, that shows the general shape of the relationship between two variables. It will not have any points plotted and although the axes should be labelled they may not be scaled.
Define the term ‘True value’
This is the value that would be obtained in am ideal measurement.
Define the term ‘Uncertainty’
The interval within which the true value can be expedcted to lie, with a given level of confidence or probability.
