limits 1 Flashcards
what is an uncertainty
an estimate of the difference between a measurement reading and the true value
interval within which a true value is expected to lie
what errors lead to uncertainty
random, systematic
what is random error
caused by fluctuations in an instruments readings as a result of uncontrollable factors such as environmental factors
this effects the precision of the results causing a wider spread about the man value
how to reduce random error
repeat measurements and calculate mean
what Is systematic error
from the use of faulty instruments or flaws in the experiments method
this error is consistent each time and affects the accuracy of all the readings obtained
how to reduce systematic error
instruments should be recalibrated or different instrument
corrections made to the technique
what Is zero error
occur when instrument gives a reading when the true reading is zero
this introduces a fixed error into the reading which must be accounted for when the results are recorded
precision =
very little spread about the mean
degree of exactness of the measurement given by the extent of random errors
precision Is given by the range of the readings
if a measurement is repeated serveral times it can be called precise as all the values are very similar to eachther
values with greater number of decimal places are more precise
accuracy=
close to the accepted value
usually expressed as an uncertainty
can be increased by repeating measurements and finding the mean
repeating helps find anomalies
repeatability =
a measurement is relatable if the original experimenter repeats the investigation using the same method and equipment
reproducibilty =
reproducible if the investigation is repeated by another person or by using different equip or techniques and getting the same result
what is the resolution
the smallest change in quantity being measured on a measuring instrument
when is data valid
can be used to give required data and gave been obtained by an acceptable method
