About accuracy and precision, Slides of Physics

Download About accuracy and precision and more Slides Physics in PDF only on Docsity! “Service, Excellence, and Empowerment” ACCURACY AND PRECISION =nt of Education  “Service, Excellence, and Empowerment” The left image shows a target hit with a high degree of accuracy, but low precision. The right image shows the target hit with high precision, but low accuracy. DarkEvil / Wikimedia Commons / Public Domain 6 2) Aurora National Science High Schéol q ed “Service, Excellence, and Empowerment” Factors affecting the accuracy of the Measuring System The basic components of an accuracy evaluation are the five elements of a measuring system such as: e Factors affecting the calibration standards e Factors affecting the work piece. e Inherent characteristics of the instrument. e Factors affecting the person, who do the measurement e Factors affecting the environment. i “Service, Excellence, and Empowerment” 1. Factors affecting the Calibration Standard: * Coefficient of thermal expansion ¢ Calibration interval ° Stability with time ° Elastic properties * Geometric compatibility a “Service, Excellence, and Empowerment” 2. Factors affecting the Work piece: Cleanliness * Surface finish, waviness, scratch, surface defects etc., * Hidden geometry ° Elastic properties * adequate datum on the work piece ¢ Arrangement of supporting work piece ¢ Thermal equalization etc. @ “Service, Excellence, and Empowerment” 5. Factors affecting Environment: ¢ Temperature, humidity etc. * Clean surrounding and minimum vibration enhance precision ¢ Adequate illumination ¢ Temperature equalization between standard, work piece, and instrument ¢ Thermal expansion effects due to heat radiation from lights ° Heating elements, sunlight and people ¢ Manual handling may also introduce thermal expansion. @ —  “Service, Excellence, and Empowerment” The above analysis of five basic metrology elements can be composed into the acronym SWIPE, for convenient reference where, S -STANDARD W —WORKPIECE | -INSTRUMENT P —PERSON E—ENVIRONMENT “Service, Excellence, and Empowerment” Sources: ° http://www.brainkart.com/article/Factors-affecting- the-accuracy-of-the-Measuring-System 5810/ ° https://www.thoughtco.com/difference-between- accuracy-and-precision-609328. Anne Marie Helmenstine, Ph.D., December 29, 2017 )