Measurement Techniques Flashcards
What is systematic uncertainty (systematic error)?
Systematic uncertainty will result in a constant error in all readings. It will cause the readings to be all above or all below the true value.
Systematic uncertainty arises from faults in instrument or sometimes poor technique when taking measurements.
Systematic uncertainty cannot be eliminated by repeating readings and then averaging.
What is random uncertainty (random error)?
Random uncertainty will result in the readings being scattered around the true value. The readings are too large or too small.
Random uncertainty may be reduced by repeating readings and averaging, or by plotting a graph and drawing a best-fit line.
Are the following examples sources of systematic uncertainty or random uncertainty?
(1) zero error on an instrument
(2) timing oscillations without the use of a reference marker, so timings may not always be made to the same point of the swing
(3) taking readings of a quantity that varies with time, involving the difficulty of reading both a timer scale and another meter simultaneously.
(4) wrongly calibrated scale
(5) reading a scale from different angles introduces a variable parallax error.
Systematic uncertainty:
Zero error on an instrument.
Wrongly calibrated scale.
Random uncertainty:
Timing oscillations without the use of a reference marker, so timings may not always be made to the same point of the swing.
Taking readings of a quantity that varies with time, involving the difficulty of reading both a timer scale and another meter simultaneously.
Reading a scale from different angles introduces a variable parallax error.
What is meant by accuracy?
What is meant by accurate readings?
Accuracy is concerned with how close a reading is to its true value.
Accurate readings are close to the true value of the quantity being measured.
What is meant by precision?
Precise readings are all close together, and are clustered closely around the average value.
