DEPARTMENT OF MECHANICAL ENGINEERING FIFTH SEMESTER ME1304 – ENGINEERING METROLOGY and MEASUREMENTS TWO MARK QUESTIONS

1.Differentiate accuracy and Uncertainty with example. Accuracy-Closeness to the true value. Example: Measuring accuracy is ± 0.02mm for diameter 25mm. Here the measurement true values lie between 24.98 to25.02 mm Uncertanity about the true value = ± 0.02mm 2. Differentiate between precision and accuracy. Accuracy-The maximum amount by which the result differ from true value. Precision-Degree of repetitiveness. If an instrument is not precise it will give different results for the same dimension for the repeated readings. 3. Differentiate between sensitivity and range with suitable example. Example: A Instrument have a scale reading of 0.01mm to 100mm. Here, the sensitivity of the instrument is 0.0lmm i.e. the minimum value in the scale by which the instrument can read. The range is 0.01 to 100mm i.e. the minimum to maximum value by which the instrument can read. 4. Deflne system error and correction., Error: The deviation between the results of measured value to the actual value. Correction: The numerical value which should be added to the measured value to get the correct result. 5. Define: Measurand. Measurand is the physical quantity or property like length, diameter, and angle to be measured. 6. Define: Deterministic Metrology. The metrology in which part measurement is replaced by process measurement. The new techniques such as 3D error compensation by CNC systems are applied. 7.Define over damped and under damped systenL Over damped-The final indication of measurement ii approached exponentially from one side. Under damped-The pointer approach the position corresponding to final reading and makes a number of oscillations around it.