Electrical Measurements Chapter: Measurement Errors
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Questions and Answers

What is the primary source of gross error?

  • Instrumental shortcomings
  • Human mistakes in reading and recording (correct)
  • Environmental effects on instrument
  • Inherent limitations of the measurement method
  • How can instrumental errors be avoided?

  • By minimizing environmental effects on instrument
  • By selecting a suitable instrument for the particular measurement application (correct)
  • By eliminating human mistakes in reading and recording
  • By taking more than one reading of the same quantity
  • What is the main reason for environmental errors?

  • Inherent limitations of the measurement method
  • Human mistakes in using the instruments
  • Instrumental shortcomings
  • Environmental effects on instrument (correct)
  • What kind of errors can be avoided by using the proper correction factor and information supplied by the manufacturer of the instrument?

    <p>Environmental errors</p> Signup and view all the answers

    What is the primary purpose of calibrating an instrument?

    <p>To correct for instrumental errors</p> Signup and view all the answers

    What is the purpose of using mirrors or knife edged pointers in instruments?

    <p>To eliminate observational errors</p> Signup and view all the answers

    What is the main difference between systematic errors and gross errors?

    <p>Systematic errors are due to instrumental shortcomings, while gross errors are due to human mistakes</p> Signup and view all the answers

    What type of error occurs due to unknown causes, even when all systematic errors have been accounted for?

    <p>Random error</p> Signup and view all the answers

    What is the purpose of taking more than one reading of the same quantity?

    <p>To minimize gross errors</p> Signup and view all the answers

    What is the definition of absolute error?

    <p>The difference between the measured value and the true value</p> Signup and view all the answers

    What is the primary reason for classifying errors into different types?

    <p>To identify the sources of errors and develop strategies to minimize them</p> Signup and view all the answers

    What is the relative error?

    <p>The ratio of absolute error to the true value of the quantity</p> Signup and view all the answers

    What is the primary limitation of gross error?

    <p>It can be minimized by taking care while reading and recording</p> Signup and view all the answers

    What is the purpose of making a new calibration under local conditions?

    <p>To reduce environmental errors</p> Signup and view all the answers

    What is the absolute error in the measurement of a voltage with a true value of 1.50 V and an indicated value of 1.46 V?

    <p>0.04 V</p> Signup and view all the answers

    What is a common source of observational error?

    <p>Parallax error while reading a meter</p> Signup and view all the answers

    What is the relative error in a measurement?

    <p>The ratio of absolute error to original value</p> Signup and view all the answers

    What can be used to reduce observational errors?

    <p>Instruments with mirrors</p> Signup and view all the answers

    A measurement instrument has a scale range of 0-2.50 V. If the true value is 1.50 V, what is the maximum absolute error possible?

    <p>1.50 V</p> Signup and view all the answers

    What is the primary difference between systematic and random errors?

    <p>Systematic errors are repeatable, while random errors are not</p> Signup and view all the answers

    What is the purpose of a concept map in understanding errors in measurement?

    <p>To visualize the different types of errors</p> Signup and view all the answers

    What is the relationship between the absolute error and the relative error?

    <p>Relative error is the ratio of absolute error to original value</p> Signup and view all the answers

    Study Notes

    Types of Measurement Errors

    • Errors occur due to human carelessness, instrument limitations, and environmental effects
    • Classified into three types:
      • Gross Errors
      • Systematic Errors
      • Random Errors

    Gross Errors

    • Occur due to human mistakes in reading, calculating, and recording data
    • Can be minimized by:
      • Taking care while reading and recording data
      • Taking multiple readings of the same quantity by different persons

    Systematic Errors

    • Instrumental Errors:
      • Due to inherent shortcomings in instruments and misuse of instruments
      • Can be avoided by:
        • Selecting a suitable instrument for the application
        • Applying correction factors after determining instrumental error
        • Calibrating instruments against a standard
    • Environmental Errors:
      • Arise from environmental effects on instruments (e.g. temperature, humidity, magnetic fields)
      • Can be avoided by:
        • Using correction factors and information supplied by the manufacturer
        • Using arrangements that keep surrounding conditions constant
        • Making new calibrations under local conditions

    Observational Errors

    • Occur due to carelessness of operators while taking readings
    • Sources of observational errors:
      • Parallax error while reading a meter
      • Wrong scale selection
      • Habits of individual observers
    • Can be eliminated by using instruments with mirrors, knife-edged pointers, and digital display instruments

    Random Errors

    • Due to unknown causes, even after accounting for systematic errors
    • Occur in high-accuracy work, due to:
      • Friction in instrument movement
      • Parallax errors between pointer and scale
      • Mechanical vibrations
      • Hysteresis in elastic members

    Absolute and Relative Errors

    • Absolute Error: difference between measured value and true value of a variable
    • Relative Error: ratio of absolute error to true value of the quantity to be measured

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    Description

    This quiz covers the topic of measurement errors in electrical measurements, including types of errors such as gross error, systematic errors, and random errors.

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