Accuracy, Precision, And Significant Figures - SS1 Physics Lesson Note
Accuracy, precision, and significant figures are important concepts in measuring and expressing the reliability and confidence of numerical values obtained through measurement with the necessary instruments. Let's take a closer look at each of them:
1. Accuracy: Accuracy refers to how close a measured value is to the true or accepted value. It indicates the absence of systematic errors in the measurement. A measurement is considered accurate if it is close to the true value, regardless of the precision of the measurement. Accuracy is determined by comparing the measured value to a known or accepted reference value.
2. Precision: Precision refers to the degree of consistency in a set of measurements. It reflects the ability to obtain the same or similar results repeatedly. A measurement is considered precise if repeated measurements yield similar results, even if they are not close to the true value. Precision is determined by the range or spread of measurements.
3. Significant Figures: Significant figures (also known as significant digits) are the digits in a numerical value that carry meaning or contribute to the precision of the measurement. They indicate the level of certainty or confidence in the measured value. The rules for determining significant figures are as follows:
- Non-zero digits are always significant (e.g., 1, 2, 3).
- Zeros between non-zero digits are significant (e.g., 505, 0.0205).
- Leading zeros (zeros before the first non-zero digit) are not significant (e.g., 0.0025 has two significant figures).
- Trailing zeros (zeros at the end of a number after the decimal point) are significant (e.g., 4.00 has three significant figures).
- Trailing zeros before an implied decimal point are not significant (e.g., 1000 has one significant figure)
Significant figures help communicate the precision of a measurement and ensure that calculations involving measured values maintain the appropriate level of precision. When performing mathematical operations with measured values, it is important to round the final result to the correct number of significant figures based on the least precise value involved.
In summary, accuracy relates to how close a measured value is to the true value, precision refers to the consistency or reproducibility of measurements, and significant figures indicate the level of precision and uncertainty in a measured value.