Flashcards
Practical Skills
Cards in this deck (19)
- 1Measurement ErrorThe difference between a measured value and the true value.
- 2anomalyThis is a freak result – judged to not fit the main trend. It should be
rejected and the reading repeated. - 3random errorThese cause readings to be either above or below the true value
Random errors are present when any measurement is made, and cannot
be corrected.
can be reduced by making more measurements and calculating a new mean. - 4systematic errorThese 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 (typically a zero
error) - 5If a systematic error is suspected,the data collection should be repeated using a different technique or a different set of equipment, and the results compared.
- 6accuracyThe closer you are to the true value the more accurate the measurement
- 7Precise measurements areones in which there is very little spread about the mean value ie. not much random error – it gives no indication of how close results are to the true value.
- 8Precise scaleHigh resolution
- 9Repeatabilitya measurement is repeatable if the same person repeats using the same method and apparatus
- 10Reproducibilitya measurement is reproducible if another person does the experiment and gets the same results
- 11If measurements are repeated, the uncertainty is calculated byfinding half the range of the measured values.
- 12If instead the measurements had all been the same:Then to get the uncertainty we examine the resolution of the instrument,
- 13For sum and differencesimply add the absolute errors
- 14For multiplication you mustadd the percentage errors:
- 15For powers,multiply the percentage uncertainty by the power:
- 16Reading (one judgement only)Thermometer
Geiger Counter
Top Pan Balance - 17Measurement (2 judgements needed)ruler
vernier caliper
micrometer
protractor
stop watch
analogue meter - 18% error for a readinghalf smallest division/mean
- 19% error for measurementsmallest division/mean value
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- AS Physics Flashcards on Practical Skills, created by Andrew Stonehouse on 11/10/2017.
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- Andrew Stonehouse
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