Workbook 1 - Measurements and Their Errors Flashcards
What are S.I. units?
A coherent system of units that all fit together. When doing calculations you need to convert measurements in S.I. units.
What are the 7 fundamental S.I. units?
- Ampere (A), the unit of electrical current
- Candela (cd), the unit of luminous intensity
- Kelvin (K), the unit of temperature
- Kilogram (Kg), the unit of mass
- Metre (m), the unit of length
- Mole (mol), the unit of quantity of a substance (how many atoms or molecules)
- Second (s), the unit of time
Other important S.I. units?
Speed - ms^-1 Area - m^2 Volume - m^3 Force (Newtons) - N or kgms^-2 Energy (Joules) - J or kgm^2s^-2
What are the 10 prefixes?
- Tera - T - 10^12
- Giga - G - 10^9
- Mega - M - 10^6
- Kilo - k - 10^3
- Centi - c - 10^-2
- Milli - m - 10^-3
- Micro - mu - 10^-6
- Nano - n - 10^-9
- Pico - p - 10^-12
- Femto - f - 10^-15
Definition of accuracy?
A measurement result is considered accurate if it is judged to be close to the true value
What is calibration?
Marking a scale on a measuring instrument. This involves establishing the relationship between indications of a measuring instrument and standard or reference quantity values, which must be applied. For example, placing a thermometer in melting ice to see whether it reads 0 degrees, in order to see if it has been calibrated correctly
What is data?
Information, either qualitative or quantitative, that has been collected
What is measurement error?
The difference between a measured value and the true value
What are anomalies?
These are values in a set of results which are judged not to be part of the variation caused by random uncertainty
What is random error?
These cause readings to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next. The effect of random errors can be reduced by taking more measurements and calculating a mean.
What is systematic error?
These cause readings to differ from the true value by a consistent amount each time a measurement is made.
Zero error?
An indication that equipment gives a false zero reading
What is evidence?
Data which has been shown to be valid
What is a fair test?
A test in which only the independent variable has been allowed to affect the dependent variable
What is a hypothesis?
A proposal intended to explain certain facts or observations
What is interval?
The quantity between readings
What is precision?
Precise measurements are ones in which there is very little spread about the mean value. It depends only on the extent of random errors
What is a prediction?
A prediction is a statement suggesting what will happen in the future, based on observations, experience or a hypothesis
What is the range?
The maximum and minimum values of the independent or dependent variables. It is important in ensuring that any pattern is detected
When are measurements repeatable?
If the original experiment repeats the investigation using the same method and equipment and obtains the same results.
When is a measurement reproducible?
If the investigation is repeated by another person or by using different equipment or techniques and the same results are obtained
What is resolution?
This is the smallest change in the quantity being measured (input) of a measuring instrument that gives a perceptible change in the reading
What is a sketch graph?
A line graph that generally shows the shape and relationship between two variables. Doesn’t have any points plotted but does need labeled axes
What is the true value?
The value that would be obtained in an ideal measurement
