Examoogle
ExamsTest SeriesRank CheckPrevious Year PapersPassBook StoreMy BooksAI Tutor
🛒0
अA
Examoogle

India's most trusted platform for competitive exam PDF books. Expert-authored, watermark-protected, instant access.

Exams & Practice
All Exams & SyllabusMock Test SeriesPrevious Year PapersPractice Questions (MCQs)Recruitment Notifications
Quick Links
Examoogle AI TutorExam NewsBook StoreMy BooksLogin / Sign Up
Support
About UsRefund PolicyPrivacy PolicyTerms of UseContact Us
© 2026 Examoogle. India's #1 competitive exam AI tutor.
🔒 SSL Secured📱 UPI Accepted🧾 GST Invoice
Examoogle

Join 60,000+ competitive exam aspirants

or with email
By continuing, you agree to ourTerms of Service&Privacy Policy
Your Cart
Subtotal₹0
Total₹0
Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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

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.

💡 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.

🔢 Key Formulas

Er=Xm−XˉE_r = X_m - \bar{X}Er​=Xm​−Xˉ — where ErE_rEr​ is the random error, XmX_mXm​ is the measured value, and Xˉ\bar{X}Xˉ is the mean of repeated measurements.

σ=∑(Xi−Xˉ)2n−1\sigma = \sqrt{\frac{\sum(X_i - \bar{X})^2}{n-1}}σ=n−1∑(Xi​−Xˉ)2​​ — represents the standard deviation used to quantify the dispersion of random errors.

⚙️ 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.

📌 Key Points
  • ▸

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

  • ▸

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

  • ▸

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

  • ▸

    They are inherent to the measurement process and instrumentation sensitivity.

✅ Advantages
  • ▸

    Statistical analysis helps in estimating the precision of measurements.

  • ▸

    Increasing sample size allows for convergence toward the true value.

❌ Disadvantages / Limitations
  • ▸

    Cannot be eliminated completely.

  • ▸

    Requires significant time for repeated measurements to ensure reliability.

🛠️ Applications / Uses
  • ▸

    Scientific research and experimental physics.

  • ▸

    Quality control in manufacturing where precision is critical.

📄 Additional Information
  • ▸

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

  • ▸

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

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

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

Core Concepts Used
Click any tag to open in AI Tutor
Measurement Uncertainty Statistical Analysis Experimental Precision
💡 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.

Related Questions

ElectricalMeasurement & Instrumentation
The calibration of a voltmeter can be carried out by using
ElectricalMeasurement & Instrumentation
A galvanometer based recorder works on the principle of ________
ElectricalMeasurement & Instrumentation
How many types of tracing systems are used in graphical representation?
ElectricalMeasurement & Instrumentation
Basic elements of a strip chart recorder are ________
ElectricalMeasurement & Instrumentation
In a strip chart recorder ________

Discussion (0)

Loading discussion...
PrevNext