SIGNIFICANT FIGURES.

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Presentation transcript:

SIGNIFICANT FIGURES

Significant Figures When a scientist makes a measurement, he or she is allowed to estimate one digit. Consequently, the last digit of any measurement is always considered to be uncertain since it has been estimated.

Significant Figures Significant digits (figures) include all measured (certain) digits plus one estimated (uncertain) digit.

Significant Figures The precision of measurement is an important part of experimentation. Precision refers to the degree of exactness with which a measurement is made and stated. This precision is indicated by the number of significant digits in the measurement.

Significant Figures accepted (actual) - experimental Accuracy is not the same thing as precision. Accuracy refers to how close to the accepted value a measurement is. We often show the accuracy of a measurement or calculation with % error. accepted (actual) - experimental % error = ---------------------------------------------------- x 100 accepted (actual)

Significant Figures How do you determine the number of significant digits in a measurement??? All nonzero digits are significant.

Significant Figures How do you determine the number of significant digits in a measurement??? 2. A zero is significant if It is the last digit to the right of a decimal. It has a bar over it. It is “sandwiched” between significant digits.

Significant Figures If a zero doesn’t fit into one of these 3 categories, it is merely a place-holder and hasn’t been measured or estimated so it isn’t significant.