This Portion of Electrical and Electronic Measurements and Measuring instruments contains Errors in Measurements and Their Statistical Analysis MCQs (Multiple Choice Questions and Answers) / Objective Type Questions and Answers.

This Section covers below lists of topics.

1. Limiting Errors (Guarantee Errors)

2. Relative (Fractional) Limiting Errors

3. Combination of Quantities with limiting Errors

4. Known Errors

5. Types of Errors

6. Systematic Errors

7. Random (Residual) Errors

8. Central Value

9. Statistical Treatment of Data

#### 1. An 0 – 10 A ammeter has a guaranteed accuracy of 1 percent of full scale deflection. The limiting error while reading 2.5 A is :

- 1%
- 2%
- 4%
- none of the above.

#### 2. A 0 -300 V Voltmeter has an error of ±2% of full scale deflection. What would be the range of reading if true voltage is 30 V?

- 24V – 36 V
- 29.4V – 30.6 V
- 20 V to 40.6 V
- none of the above.

#### 3. A wattmeter has a full scale range of 2500 W. it has an error of ±1% of true value. What would be the range of reading if true power is 1250 W ?

- 1225 W – 1275 W
- 1245 W – 1255 W
- 1200 W – 1300 W
- 1237.5 W – 1262.5 W

#### 4. Power in d.c circuit is measured by measuring the voltage across and current through the circuit.The voltage and current measurements are made to an accuracy of ±2% and ±3% respectively. The errors are limiting errors. The error in measurement of power is:

- ±2%
- ±3%
- ±6%
- ±5%

#### 5. The power in a circuit is measured by measuring a current through a resistor. The current is measured with an accuracy of ±1.5% and the tolerance band of resistor ±0.5%. the errors are limiting or guarantee errors. The accuracy with which power is measured is :

- ±1.125%
- ±3.5%
- ±2%
- ±2.5%

#### 6. In an permanent magnet moving coil ammeter the deflection of the pointer is proportional to product of flux density of magnetic field produced by the permanent magnet and current in the moving coil. if the strength of permanent magnet becomes 95% of the original, The meter gives erroneous reading resulting into error. This error can be classified as:

- Gross Error
- Systematic error
- Random Error
- none of the above.

#### 7. The voltage of circuit is measured by a voltmeter having an input impedance comparable with the output impedance of the circuit thereby causing error in voltage measurement. This error may be called

- Gross Error
- Random Error
- Error cause by misuse of instrument
- Error caused by loading effect.

#### 8. The mean Deviation D in terms of deviation from the mean value of *n* reading is

- (∑|d|)/n
- (∑d)/n
- (√∑d^2 )/n
- √((∑d^2 )/n)

#### 9. A set of readings has a wide range and therefore it has:

- low precision
- high precision
- low accuracy
- high accuracy

#### 10. The Gaussian distribution can be mathematically expressed as:

- y = (h/√π) e
*(h*^{2 }x^{2}) - y = - (h/√π) e
*(h*^{2 }x^{2}) - y = (h/π) e
*(-h*^{2 }x^{2}) - y = (h/√π) e
*(-h*^{2 }x^{2})

*(-h*

^{2 }x^{2})#### 11. for a Gaussian distribution, the probable error is *r. *This means that:

- area under curve between ±r limits to 0.5
- half of the observed values lie between ±r limits
- the chances that an additional observation will lie between ±r limits are 50 percent
- all the above.

#### 12. Two resistances 100Ω ± 5Ω and 150Ω ± 15Ω are connected in series. If the deviations are standard deviations, the resultant resistance can be expressed as:

- 250Ω ± 20Ω
- 250Ω ± 10Ω
- 250Ω ± 15.8Ω
- 250Ω ± 10.6Ω

#### 13. if the result of a measurement is expressed as x̅ ± 3σ where x̅ = mean value and σ = standard deviation ,it means that :

- approximately 99 percent of the readings lie between x̅ ± 3σ limit
- 26 readings out of 1000 will lie outside ± 3σ limit
- the odds for any readings to lie within ± 3σ limit
- All of the above.

#### 14. A batch of resistors have a mean value of 100 Ω and a standard deviation σ = 0.2 Ω. The probability corresponding to 2σ is 0.9546. The value of odds that randomly selected resistor will lie within 100.00 ± 0.40 Ω is:

- 1 to 1
- 2.15 to 1
- 21 to 1
- 256 to 1.

#### 15. According to Chauvenet’s criterion, a reading out of set of *n *reading should be rejected if the probability of obtaining the particular deviation from mean is :

- less than 1/2n
- greater than 1/2n
- less than 1/n
- less than 1/√2n

#### 16. if the confidence level is 0.95, then the value lying outside the confidence interval are:

- 1 in 5
- 1 in 20
- 1 in 100
- 1 in 1000.

#### 17. Uncertainty distribution is used for:

- analysis of multi-sample data
- analysis of single sample data
- analysis of both multi and single sample data
- none of the above.