2.2 Measurements And Uncertainties Flashcards
(14 cards)
What is an error interval
The difference between the true value and the result obtained
What is a random error
Occur when a measurement is being made
Measurements vary unpredictably
What causes random errors
Caused by external factors / difficulty reading measuring device
How can random errors be corrected
Can’t be corrected but can be mitigated with repeat experiments
What is a systematic error
When the measurement differs from the true value by the same amount each time
Eg zero error is when the value isn’t recorded at zero so all the values are off by the measured zero value
What causes systematic errors
The way measurements are taken or a faulty measuring device
They can be corrected
What is accuracy
How close the measurement is to the true value by
What is precision
How close the measurements are relative to each other
What is the equation to calculate percentage uncertainty in a single reading
% uncertainty = (absolute uncertainty / measured value) x 100
What is the equation to calculate percentage uncertainty for repeated readings
% uncertainty = (half the range / average value) x 100
What is the equation to calculate percentage uncertainty in a gradient
% uncertainty = ( (gradient of best fit - gradient of worst fit) / gradient of best fit ) x 100
How to calculate overall uncertainty when quantities are added or subtracted
Add the uncertainties together
How to calculate overall uncertainty when quantities are multiplied or divided
Add the uncertainties together
How to calculate overall uncertainty when quantities are raised to power of n
Multiply uncertainty by n
