ACCURACY IN MEASUREMENTS

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• Q1: State the five basic elements of Metrology.
  Ans: The five basic elements are as follows:

  • ➔ Standard
  • ➔ Work piece
  • ➔ Instrument
  • ➔ Person
  • ➔ Environment
• Q2: Define Accuracy.
  Ans: Accuracy is the degree to which a measured value is close to the true or actual value.
• Q3: What are Measurement Errors?
  Ans: Measurement errors are the differences between the measured value and the true value of a quantity.
• Q4: State the classification of Errors.
  Ans: Classification of errors are:

  • ➔ Systematic Errors
  • ➔ Random Errors
  • ➔ Gross Errors
• Q5: What are Systematic or Controllable Errors?
  Ans: Systematic or controllable errors are predictable errors that occur due to known causes and can be corrected or minimized.
• Q6: Name some Systematic or Controllable Errors.
  Ans: Some systematic errors are:

  • ➔ Instrumental errors
  • ➔ Environmental errors
  • ➔ Observational errors
• Q7: What is a Calibration Error?
  Ans: Calibration error is the error that occurs when a measuring instrument is not properly calibrated against a standard.
• Q8: State some Causes of Systematic or Controllable Errors.
  Ans: Causes are:

  • ➔ Faulty instruments
  • ➔ Improper calibration
  • ➔ Environmental conditions (temperature, humidity)
  • ➔ Human observation errors
• Q9: What is Stylus Pressure?
  Ans: Stylus pressure is the force applied by the measuring stylus on the surface of the workpiece during measurement.
• Q10: What are Random Errors?
  Ans: Random errors are unpredictable errors that occur due to unknown and uncontrollable factors during measurement.
• Q11: State some characteristics of Random Errors.
  Ans: Characteristics are:

  • ➔ Occur irregularly
  • ➔ Cannot be predicted
  • ➔ Vary in magnitude and sign
  • ➔ Can be reduced by repeated measurements
• Q12: State some Random Errors.
  Ans: Some random errors are:

  • ➔ Human reading errors
  • ➔ Environmental fluctuations
  • ➔ Instrument noise
• Q13: What is Calibration?
  Ans: Calibration is the process of comparing a measuring instrument with a standard to ensure accuracy.
• Q14: What is Repeatability?
  Ans: Repeatability is the ability of a measuring instrument to give the same result when the same measurement is repeated under identical conditions.
• Q15: What does SWIPE mean in metrology?
  Ans: SWIPE stands for:

  • ➔ Standard
  • ➔ Workpiece
  • ➔ Instrument
  • ➔ Person
  • ➔ Environment