2.1: measurements, errors and uncertainties Flashcards
what is a control variable
something that must be kept constant to prevent it affecting the dependent variable
what is meant by the repeatablitity of results
similar results would be obtained from repeats of the same measurent from the same experimental set up
what is meant by the reproducibility of results
similar results would be obtained from repeats by different people with different equipment
how can you ensure a metre rule is held vertically
use a plumb line, set square or spirit level
hwo do you avoid parallax error
ensure eye, object and scale are all in line with each other or ensure object and scale are directly adjacent to each other
what is meant by the term random error
errors that cause the measurement to vary in unpredictable ways
what is a systematic error
an error that causes the measurements to differ from the true value by a consistent amount
what is a zero error
an error thst occurs due to the measuring instrument reading a non zero reading when the measured quantity is zero
what is meant by the accuracy of a result
how close a measurement is to the ‘true’ or accepted value
what is meant by the precision of results
how close repeated measurements are to each other
what is meant by the resolution of a measuring instrument
the smallest change in quantity that can be measured
what determines the resolution when using a multimeter
scale selected
how do you find absolute uncertainty from repeated readings
± ½ range of repeats
how do you estimate uncertainty whenrepeated results are identical
± ½ resolution of instrument
how do you calculate percentage uncertainty
(absolute uncertainty ÷ calculated value) × 100
what do you do to the uncertainties when walues are added or subtracted
add absolute uncertainties
what do you do when uncertainties of values are multiplied or divided
percentage uncertainties added
what do you do when uncertainties of values are multiplied or divided
percentage uncertainties added
what do you do when quantities are raised to a power
multiply percentage uncertainty by power
how to find uncertainty in gradient
± (line of best fit - line of worst fit)
