uncertainties Flashcards
(31 cards)
What is the difference between accuracy and precision?
Accurate: how close a result is to the true value
Precise: how close related results are to one another
what is an error?
the difference between an individual result and the true value
when errors occur they introduce uncertainties
what is an uncertainty?
an estimate of the range values within which the true value lies for a measurment
smaller uncertainty, smaller error, more accurate value
what is a zero error?
when there is no input to the device, it still shows a reading
fix by calibrating
what is the uncertainity of a measurment that read 13.45g?
how do uncertainities arise?
- errors in methods
- resolution of instruments
what is a systematic error?
an unavoidable flaw in the method which results in the same error being made each time a measurement is taken
what is a random error?
a flaw in the method which results in a different error being made each time a measurement is taken.
* more difficult to account for and so the associated uncertainty is larger (different people have different
usually due to a human element
what is the total absolute uncertainty?
the uncertainity assigned to a measurement as an absolute value
* the smallest division
what is a relative uncertaibity?
absolute uncertainity/ measured value
a fraction of the
cannnot be expressed as ±
percentage uncertainty (single value)
relative uncertainity x 100
can be expressed as ± 1.81%
what do you do he uncertaininty when adding or subtracting?
Add the absolute uncertainty
what do you do to the uncertainity when dividing or multiplying?
Add the relative uncertainties to get a relative uncertainty which could be calculated into a percentage or absolute
what do you do the uncertainity when multiplying or dividing by a constant?
Multiply / divide the absolute uncertainties
what do you do to an uncertainty when raising to a power?
Multiply the relative uncertainty by the magnitude of the power
Calculate the absolute uncertainty and percentage uncertainty of A+B and A-B ?
Calculate the absolute and percentage uncertainty of AB and A/B
Calculate the absolute and percentage uncertainty of Ak and A/k
Calculate the percentage and absolute uncertainty of A ^^n
Calculate the percentage and absolute uncertainty of A ^^n
Percentage uncertainty Q
What is the uncertainty of time?
Always 0.2 s because of reaction time
