Measurements and Errors Flashcards
Why may cause random error?
Using a ruler or any other type of analogue measuring requiring a scale.
What is the resolution of any measuring equipment?
Smallest scale division
How do you calibrate a micrometer?
- Turn the ratchet thimble to ensure the jaws are not compressed.
- If there is a zero error, subtract it from every measurement.
How do you find the line of worst fit?
The max or min gradient while still crossing all error bars.
How do you find the uncertainty from a graph?
The difference between the line of best fit and worst fit.
What is the absolute uncertainty of a reading and a measurement?
- Reading: same as resolution (one judgement)
- Measurement: double resolution (two judgements)
How do you combine uncertainties in the same unit?
Add the absolute uncertainties.
How do you combine uncertainties in different units?
Add the uncertainties as percentages.
State the two methods for reducing % uncertainty.
- Use an instrument with a smaller resolution.
- Measure a larger quantity.
What is the absolute uncertainty of repeated measurements?
Half the range (unless the range is less than the instrument resolution).
How can the line of best fit gradient be calculated using uncertainties?
Gmax – Gmin /2
How is the % uncertainty of the intercept and gradient calculated?
(1/2 range) / mean
100 x 1/2 (Gmax - Gmin) / mean
