ISA Skills Flashcards
Accepted Value
The value of the most ACCURATE measurement available.
Sometimes called the true value
Accuracy
Measure of confidence in a measurement.
Expressed as an upper and lower limit (eg 9.8+-0.3ms^-2)
Dependent variable
The variable which value changes as a result of a change in the independent value.
Usually plotted on the y-axis
Error
The difference between a measurement and its accepted value.
NOT a mistake made in taking a reading
Indenpendat variable
Physical quantities whose values are controlled by the experimenter.
Plotted on the x and affects the dependant
Linearity
constant gradient and y=mx+c can be used
Mean vlaue
Calculated by adding the readings and dividing by the number of readings
Percentage uncertainty
(uncertainty)/(mean value)*100
Precision
The degree of “exactness”(Number of sig figs) to which a measurement can be obtained consistently
How does one calculate the precision of a measurement that has multiple values (mean value)
Take half the max range
What is the precision of an instrument
The smallest non-zero reading that can be meau
Random error
Errors with no pattern or bias.
Are unpredictable.
Effect of these errors are reduced by taking more values
Range
Difference between smallest and largest values of a set
Reliability
The extent to which measurements of a quantity remain consistent over repeated measurements of the same quantity under the same conditions.
How can one find the reliability from a graph
Look how close the measurements are to the best fit line
Why use the gradient rather than a point to find the value of a quantity
using just one point is very unreliable and the more points you take, the more accurate the results become. a gradient is essential a multitude of points in one
How does one calculate gradient from a graph
= change in y/change in x *must use at least an 8cmx8cm triangle
How many sig figs should a value be given to
The minimum used but always more than 1
Systematic error
error which is the same throughout an experiment e.g. background radiation
Parallax error
error in readings caused by the shifting position of the observer, relative to the measuring device
When is parallax particularly an issue
in measuring curved edges
What does a parallax error imply for the uncertainty in a measurement
Always higher than it would be otherwise
