MEASUREMENT

MEASUREMENTA. 3 Parts to any measurement

1. Numerical Value2. Unit (denotes scale)3. Estimate of uncertainty

B. Lab Measurement-proper number of sig figs1. Sig figs depend upon instrument

a) Definitely known scale, divisions plus one estimated “doubtful” digit

b) Last digit is estimate, represents uncertaintyc) ALWAYS estimate to one place beyond smallest

scale divisiond) Measurement limited by uncertainty (more digits

does not mean more precise!)

MEASUREMENT (CONTINUED)C. Precision and Accuracy

1. Accuracy-most known true value2. Precision-limited by uncertainty of

measuring device

D. Experimental Error1. NOT from careless mistakes or error in

procedure!2. Unavoidable-always consider sources and

magnitude.