Quantities and Measurement Flashcards
(10 cards)
Differences between random error and systematic error
Magnitude: Random is different but systematic is the same
Sign: Random is different but systematic is same
Sources of random error
Inability of observer to repeat action precisely (e.g. inconsistent reaction time)
Environmental conditions (e.g. temp)
Limited sensitivity of apparatus
Sources of systematic error
Poor experimental technique (consistent error)
External factor (e.g. background radiation)
Apparatus (e.g. zero error/poor calibration)
How are precision and accuracy related to systematic error and random error
Accuracy affected by systematic error
Less systematic error –> avg closer to true value
Precision affected by random error
Less random error –> smaller spread of values
sf/dp rules for absolute or actual uncertainty
Actual uncertainty rounded to 1sf, percentage rounded to 2sf
Measured value must be to same precision as uncertainty
How to find change in vector
V_f - V_i
How can a graph indicate presence of random error
Data points scattered above and below the line by different amount from the line
How can graph indicate presence of systematic error
Best fit line does not pass through origin
Why does drawing best fit line reduce effect of random error
Sum of positive and negative errors are minimised, reducing random error
State and explain whether random and/or systematic errors are likely to be present when a student uses a micrometer screw gauge to take the measurements of the diameter of a ball bearing to be used in an experiment.
Random error is present due to unevenness in the object being measured. The diameter measurements obtained will spread around an average value, with some being larger and some smaller than the average value.
Systematic error will occur if there is calibration error in the measuring instrument (zero error) or there is incorrect measurement technique
