1. Percent Error

2. Percent Error At the conclusion of our time together, you should be able to: 1.Define experimental error, relative error and percent error 2. Determine percent error for an experiment

3. How to Determine Experimental Error Error = experimental – accepted value

4. Percent Error % Error = (experimental – accepted) x 100 accepted value

5. Example of Percent Error Your instructor has just massed a penny using 3 different balances. One balance measured 2.3 g, another measured 2.55 g and a third measured 2.49865 g. Determine the average mass of the penny. 2.3 g + 2.55 g + 2.49865 g = 7.34865 g ? 7.3 g /3 = 2.4333333 g ? 2.4 g

6. Example of Percent Error Ex. Err. = 2.4 g – 2.520 g = -0.12 g Rel. Err. = -0.12 g 2.520 g = -0.047619 = -0.048 % Err. = -0.048 x 100 = -4.8 % error If the standard mass of a United States penny is 2.520 g, determine the experimental error, relative error and percentage error in the measurements.

7. Percent Error Let’s see if you can: 1.Define experimental error, relative error and percent error 2. Determine percent error for an experiment

8. Exit Quiz Percent Error Your instructor has just measured the diameter of a dime using 3 different measuring devices. A ruler measured the diameter as 17.9 mm, a caliper measured 17.7 mm and a micrometer measured 17.788 mm. Determine the average diameter with the correct number of significant figures. 17.9 mm + 18.0 mm + 17.788 mm = 53.688 mm ? 53.7 mm /3 = 17.9 mm ? 17.9 mm

9. Exit Quiz Percent Error Ex. Err. = 17.9 mm – 17.80 mm = 0.10 mm Rel. Err. = 0.1 mm 17.80 mm= 0.056179775 = 0.06 % Err. = 0.06 x 100 = 6 % error If the standard diameter of a United States dime is 17.80 mm, determine the experimental error, relative error and percentage error in the measurements.