Unit 3 Flashcards
Absolute uncertainty
Uncertainty given as a fixed quantity e.g. 7+-0.6V
calibration
Comparing the reading of one instrument with another of known accuracy. Making sure that a scale reads 0 before measurements are made is also an example of calibration
Control variable
Any factor that is held constant in a scientific experiment
Dependendent variable
The variable that is being measured or tested in an experiment
Fair test
One in which only the independent variable has been allowed to affect the dependent variable
gradient
The change in y-axis over the change in x-axis between two point. If the graph is curved, a tangent can be drawn to calculate the gradient at a specific point
Independent variable
The factor that is altered in a scientific experiment in order to affect the dependent variable
Micrometer Screw gauge
A tool used for very accurate measurements of distance, they have a resolution of 0.01mm, and a range of 25mm
Percentage uncertainty
Uncertainty as a percentage of the measurement
Random error
The unpredictable variation in a measurement. These can be reduced by taking many repeated measurements and calculating the mean.
Range of an instrument
The range of values that a tool can measure with its specified resolution
Resolution
The smallest change in quantity that causes a visible change in the reading that a measuring instrument records
Systematic error
Causes all the readings to differ from the true value by a fixed amount. Systematic errors cannot be corrected by repeat readings, instead a different technique or apparatus should be used.
Uncertainty
The bounds in which the accurate value can be expected to lie e.g. 20ºC +- 2ºC, the value could be between 18-22ºC
Variable
Any factors that can change or be changed
