Measurements Flashcards
What are the seven base measurements?
Length, Mass, Time, Electric Current, Temperature, Luminosity and Amount of Substance
What are the units for the seven base measurements?
Meters (m), Kilograms (Kg), Seconds (s), Amperes, (A), Kelvin (K), Candela (cd) and Moles (mol)
Name the prefixes from largest to smallest (Standard Form)
Terra (x10¹²), Giga (x10⁹), Mega (x10⁶), Kilo (x10³), Centi (x10⁻²), Milli (x10⁻³), Micro (x10⁻⁶), Nano (x10⁻⁹), Pico (x10¹²), Femto (x10⁻¹⁵)
What is a random error?
A Measurement that varies due to unpredictable circumstances.
Is there a way to prevent a random error?
No you cannot prevent them, but you can repeat the test to try and get some new averages.
What is a systematic error?
A measurement that varies similarly each time.
How do we correct systematic errors?
You will need to find a new technique for taking measurements.
What is the difference between precision and accuracy?
Precision is how close measurements are to each other and the mean. Accuracy is how close measurements are to the true value.
What is resolution?
The smallest change in a quantity that is being measured that gives a noticeable change in the reading.
What is the difference between a repeatable test and reproducible test?
A repeatable test is performed by the person who originally did the experiment with the original equipment or technique. A reproducible test is where a different method or equipment can be used but the same results will be achieved.
How do we work out the absolute uncertainty?
It is no smaller than ± half of the smallest division. (E.g. if it’s 1cm the absolute uncertainty will be ±0.5
What is fractional uncertainty?
The absolute uncertainty divided by the measured value. If there are multiple readings, just use the mean.
What is percentage uncertainty?
The fractional uncertainty multiplied by 100.
