3 - Making Measurements And Analysing Data Flashcards
What is the error of a measurement?
The difference between the measured value and the value of the quantity.
What is the absolute uncertainty of a measurement?
And estimate of the maximum error of a measurement.
How is the absolute uncertainty of a mean estimated?
+ - half the range
How are uncertainties combined when two or more measurements are added or subtracted.
The absolute uncertainties are added together.
How are uncertainties combined when two or more measurements are multiplied or divided by each other?
The percentage uncertainties are added together.
How are the uncertainties combined when a measurement is raised to a power?
The percentage uncertainty is multiplied by the power.
What do error bars on a graph represent?
The absolute uncertainties in the measurement data.
What do worst acceptable lines on a graph show?
The expected range of possible positions of the line of best fit.
What is a random error?
An error that causes readings to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next.
How can the effect of random errors be reduced?
By making more measurements and calculating a mean.
What is a systematic error?
An error that causes readings to be different from the true value by a predicted amount.
What is a zero error?
When an instrument does not read zero when it should.
What is a parallax error?
The error that occurs when the line of sight of the person making a measurement is not perpendicular to the scale.
What effect do random and systematic errors have on a graph?
Random error is responsible for the scatter of points about the line of best fit; systematic error moves the line of best fit away from where it should be.
What is an accurate measurement?
A measurement that is close to the true value.
