MDCAT, NMDCAT, Mastering Significant Figures & Measurement Uncertainty-6

Significant figures help describe the accuracy and precision of measurements in physics. All non-zero digits are significant, while zeros may or may not be significant depending on their position. Zeros between non-zero digits are always significant, but zeros before the first non-zero digit are not significant. Trailing zeros after a decimal point are significant. In multiplication and division, the final answer should contain the same number of significant figures as the quantity with the least significant figures. In addition and subtraction, the answer should be rounded to the smallest number of decimal places present in the given data. Rounding rules are important in measurements. If the discarded digit is less than 5, the retained digit remains unchanged. If it is greater than 5, the retained digit increases by one. Precision refers to how small the measurement uncertainty is and depends on the measuring instrument’s least count. Accuracy describes how close a measurement is to the true or accepted value. Smaller percentage uncertainty means greater accuracy. Uncertainty is unavoidable in all measurements because every instrument has limited precision. Fractional uncertainty is found by dividing absolute uncertainty by the measured value, while percentage uncertainty is obtained by multiplying fractional uncertainty by 100.