BRAINCAKEAbsolute, Fractional and Percentage Uncertainty
Every measurement has an uncertainty: the interval within which the true value is expected to lie. A length written as 25.0 ± 0.1 cm is expected to lie between 24.9 cm and 25.1 cm.
The absolute uncertainty is the ± value itself (0.1 cm here). It has the same units as the measurement.
The fractional uncertainty is the absolute uncertainty divided by the measured value, and the percentage uncertainty is the fractional uncertainty × 100%:
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More in Measurements and Errors
- Converting Units
- Random and Systematic Errors
- Precision, Repeatability and Reproducibility
- Resolution and Accuracy
- Combining Uncertainties
- Uncertainties on Graphs
- Uncertainty in a Gradient
- Estimation and Orders of Magnitude
All 12 lessons in Measurements and Errors · All AQA AS-level Physics topics