Topic 1 : Measurement and Uncertainties Flashcards
1
Q
Temperature SI Unit
A
Kelvin (K)
2
Q
Distance SI Unit
A
Meters (m)
3
Q
Current SI Unit
A
Ampere (A)
4
Q
Time SI Unit
A
Second (s)
5
Q
Amount of Substance SI Unit
A
Mole (mol)
6
Q
Mass SI Unit
A
Kilogram (kg)
7
Q
Light Intensity SI Unit
A
Candela (cd)
8
Q
Derived quantities
A
- Derived quantities have units that are combinations of the fundamental units
- e.g. speed (m/s) or acceleration (m/s)
9
Q
Analog measuring device vs Digital measuring device
A
analog measuring device is where you have to estimate last digit, somewhere between 2 digits whereas digital measuring device gives an exact last digit
10
Q
Accuracy
A
how close an experimental value is to the true value
11
Q
Uncertainty
A
used to estimate the likely ranges in which the true value will lie
12
Q
Random error
A
- error due to the person measuring, rather than the instrument
- affects the precision of the reading
13
Q
Random Uncertainties
A
- Random uncertainties/errors occur in any measured quantity
- The more measurements are taken, the closer the mean value of the measurements is likely to be to the “true” value of the quantity
- Taking repeat readings and calculating an average → reduces the effect of random uncertainties, improves the accuracy of the results
14
Q
Parallax error
A
eye viewing meniscus at an angle rather than eye-level with the reading and perpendicular to the scale
15
Q
Systematic error
A
- due to the instrument “out of adjustment” or poorly calibrated (e.g. voltmeter having a zero offset error or meter stick rounded on one end)
- affects the accuracy of the reading
- Taking repeats using the same method does not reduce systematic errors
