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Back to Practice Questions
ElectricalMeasurement & Instrumentation
PrevNext

Error due to unknown reason is called?

A

Gross error

B

Random error

C

Systematic error

D

All of the above

Correct Answer

тЪЩя╕П TE тАв Technical Concept & PrincipleElectricalMeasurement & Instrumentation
Option B

Random error

Quick Summary:

Random errors are uncertainties in measurements caused by unpredictable fluctuations in experimental conditions. They are also known as accidental or chance errors because their exact causes are unknown and cannot be completely eliminated.

тЪЩя╕ПTETechnical SolutionConcept & Principle
ЁЯТб Explanation

Random errors are uncertainties in measurements caused by unpredictable fluctuations in experimental conditions. They are also known as accidental or chance errors because their exact causes are unknown and cannot be completely eliminated.

ЁЯФв Key Formulas

Er=XmтИТX╦ЙE_r = X_m - \bar{X}ErтАЛ=XmтАЛтИТX╦Й тАФ where ErE_rErтАЛ is the random error, XmX_mXmтАЛ is the measured value, and X╦Й\bar{X}X╦Й is the mean of repeated measurements.

╧Г=тИС(XiтИТX╦Й)2nтИТ1\sigma = \sqrt{\frac{\sum(X_i - \bar{X})^2}{n-1}}╧Г=nтИТ1тИС(XiтАЛтИТX╦Й)2тАЛтАЛ тАФ represents the standard deviation used to quantify the dispersion of random errors.

тЪЩя╕П Working Principle

Random errors arise due to factors like minute changes in supply voltage, slight variations in mechanical friction, or small fluctuations in ambient temperature during the measurement process. Since these factors vary continuously and unpredictably, the results of repeated measurements oscillate around a mean value.

ЁЯУМ Key Points
  • тЦ╕

    Random errors follow a statistical distribution, typically Gaussian or Normal distribution.

  • тЦ╕

    They can be minimized by taking a large number of readings and calculating their arithmetic mean.

  • тЦ╕

    Unlike systematic errors, random errors cannot be corrected by calibration.

  • тЦ╕

    They are inherent to the measurement process and instrumentation sensitivity.

тЬЕ Advantages
  • тЦ╕

    Statistical analysis helps in estimating the precision of measurements.

  • тЦ╕

    Increasing sample size allows for convergence toward the true value.

тЭМ Disadvantages / Limitations
  • тЦ╕

    Cannot be eliminated completely.

  • тЦ╕

    Requires significant time for repeated measurements to ensure reliability.

ЁЯЫая╕П Applications / Uses
  • тЦ╕

    Scientific research and experimental physics.

  • тЦ╕

    Quality control in manufacturing where precision is critical.

ЁЯУД Additional Information
  • тЦ╕

    Gross errors occur due to human negligence, such as misreading an instrument scale or incorrect adjustment.

  • тЦ╕

    Systematic errors are due to identifiable causes like calibration defects, loading effects, or environmental factors that shift the mean away from the true value.

ЁЯУК Diagram / Illustration
Classification of ErrorsRandom Error: Unpredictable and Unknown CausesSystematic Error: Known or Determinable CausesGross Error: Human Mistake in Reading/Recording
тЬЕ

B is correct тАФ Random errors represent unpredictable measurement uncertainties resulting from factors whose origins are unknown or uncontrollable.

Core Concepts Used
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Measurement Uncertainty Statistical Analysis Experimental Precision
ЁЯТб EXAM TIP

In exams, remember that if an error can be 'calibrated out', it is Systematic; if it varies based on individual reading, it is Random.

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