Module 2 - 2.2.1 Measurements and Uncertainties Flashcards

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1
Q

Random Errors

A

Caused by unknown and unpredictable changes during the experiment
e.g. changes in instrument/environmental conditions
e.g. human errors

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2
Q

Systematic Errors

A

Introduced by an inaccuracy in the apparatus or its use
Errors are present in all values and can be removed once identified
e.g. zero errors

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3
Q

Accuracy

A

The degree to which a value obtained by an experiment is close to the true value

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4
Q

Precision

A

The degree to which repeated values collected under the same conditions in an experiment show the same results
- the smaller the range of repeated values, the higher the precision
(not affected by systematic errors)

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5
Q

Resolution

A

The smallest change in a quantity that an instrument can measure

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6
Q

Absolute Uncertainties

A

The smallest division on the measuring instrument used
(for a stop watch use reaction time)

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7
Q

Percentage Uncertainty

A

absolute uncertainty/measured value x100%

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8
Q

When multiplying variables

A

Add the percentage uncertainties together

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9
Q

How to Read a Micrometer

A
  • place the object between the jaw of the micrometre
  • the horizontal scale is called the barrel scale
  • this gives a reading of millimetres and half millimetres
  • the vertical scale is called the thimble scale
  • read the barrel scale by looking at the edge of the thimble
    • top row of axis = mm
    • bottom row of axis = half mm
    • e.g. gives 14.5mm
  • find where the thimble scale lines up exactly with the barrel scale axis
    • each mark represents 0.01mm
    • e.g. if read 33, add 0.33 to previous reading
  • overall gives 14.83mm
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