R-AEPHY-1

SIS Stuff in Physics

• Accuracy: how close the measurement is to the true value of the dimension being measured

  • Either accurate or not accurate. DO NOT say "reasonably"
  • $\pm 5$% of the quantity measured (from the accepted value?)

• Precision: In terms of a measuring instrument, the fineness of the scale on the instrument. In terms of experimental precision, how far apart from the average experimental value, the individual measurements are spread.

• Reliable: when the results are consistent

  • Do more trials to make it more reliable

• Validity: There is no variable affecting the investigation other than the deliberate experimentation of the independent variable and the resulting response is the dependent variable.

• Uncertainty/Error

• 3 types!!!

  • Measurement: unavoidable, property of the measuing instrument
    • Absolute error:
      • • of the instruments, = 1/2 of the smallest unit of scale on the instrument. e.g. 30cm with millimetre increments, the absolute error is $\pm$0.5mm
    • Percentage error:
      • %$u = \frac{absolute}{value \ measured} \times 100$
  • Systematic errors: affect the results such that all measurements are skewed away from the ideal values of the data. Not necessarily(?) by the same amount.

e.g. 3 measurements were taken:

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