Practical Skills - Uncertainty

Practical Skills - Uncertainty

1. Finding uncertainty

   • For single readings, uncertainty is the precision of the measuring instrument.
   • For multiple readings, find the range of results and then half the range to find uncertainty.
   • To find percentage uncertainty, divide the numerical uncertainty by the measured value.

2. Combining uncertainties

   • When adding or subtracting values, their overall uncertainty is equal to the sum of their uncertainties.
   • When multiplying or dividing values, their overall percentage uncertainty is equal to the sum of their percentage uncertainties.

3. Finding the most accurate measurement

   • Out of several measurements, the measurement with the lowest percentage uncertainty is the most accurate.

4. Reducing uncertainty

   • Use more precise apparatus (usually involves change in measuring instrument.)
   • Calibrate measuring instrument by measuring a known value and altering measurements taken with the instrument accordingly.
   • Increase the size of the measurements taken (percentage uncertainty is inversely proportional to the magnitude of the measurement taken.)