measurements and errors Flashcards
(21 cards)
how to find absolute uncertainty of a range of data
absolute uncertainty = range/2
how to find percentage uncertainty of a range of values
percentage uncertainty = (absolute uncertainty/mean value)x100
formula for percentage uncertainty of a value
absolute uncertainty/value x100
how to calculate uncertainty when adding or taking away values
- add absolute uncertainty’s
how do you calculate uncertainty’s when multiplying or dividing values
- add the percentage uncertainty
how to find the percentage uncertainty of a value raised to a power
- x percentage uncertainty by value
what is a random error
how can they be reduced
unpredictable fluctuations in a devises readings from uncontrollable factors
they can be reduced by doing multiple readings and taking an average
what is a systematic error
error that occours consistently of the same magnitiude in readings taken by equipment
caused by a fault in the machine or method
what is zero error
type of systematic error where the instrument gives a reading even tho the true reading is zero
what does a zero error mean in a reading
the uncertainty is the full resolution as there is an uncertainty in both ends of the measurement
difference between a measurement and a reading
measurement has a zero error and a reading does not
how to find the uncertianty is a mean
range/2
what is an assumed uncertianty
the uncertainty in the measurement is ‘1’ of the last sig fig
how to find the uncertainty in a gradient
- draw both lines of wrost fit, use the one that is the ‘worst’. Find the gradeint
use : difference in two gradients/LOBF x100
what is specific about exponential decay
percentage decrease has the same relative drop in y for any regular interval of x
what is a full scale deflection
maximum value of a data logger
what is a precise measurement
the measurements are consistant, do not fluctuate too much around a mean
repeatability
experiment can be repeated by the same persion to get same results
reproducible
experiment can be reproduced by another person to yield the same results
resolution
smallest change in the quantity being measured that give a recognizable change in the reading
accuracy
how close a measurement is too the true value
