[MCQ] Instrumental Errors MCQ|Electrical Measurement Errors MCQ

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Notes on Instrument Errors

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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 :
(a) 1% (b) 2%
(c) 4% (t/) none of the above.
A 0 – 300 V voltmeter has an error of ± 2% of full scale deflection. What would be the range of readings if true voltage is 30 V ?
(a) 24 V – 36 V (b) 29.4 V – 30.6 V
(c) 20 V to 40 V (d) none of the above.
A wattmeter has a full scale range of 2500 W. It has an error ± 1% of true value. What would be range of reading if true power is 1250 W ? (a) 1225 W – 1275 W (b) 1245 W – 1255 W
(c) 1200 W – 1300 W (d) 1237.5 W- 1262.5 W.
Power in a d.c. circuit is measured by measuring the voltage across and current through the circuit. The v.oltage 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 :
(a) ± 2% (b) ± 3%
(c) ± 6% (J) ± 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 the resistor ± 0.5%. The errors are limiting or guarantee errors. The accuracy with which power is measured is :

(a) ± 1.125%
(c) ± 2%
(b) ± 3.5%
(d)±2.5%

In a 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 the current in the moving coil. If the strength of the permanent magnet becomes 95% of the original, the meter gives erraneous reading resulting into error. This error can be classified as :
(a) Gross error (b) Systematic error
(c) Random error (d) none of the above.
The voltage of a 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
(fl) Gross error
(b) Random error
(c) Error caused by misuse of instrument
(d) Error caused by loading effect.
The mean deviation D in terms of deviations from the mean value of n readings is

A set of readings has a wide range and therefore it has :
(a) low precision (b) high precision
(c) low accuracy (d) high accuracy.

y = number of readings at a deviation x and b is precision index.

For a Gaussian distribution, the probable error is r.
This means that:
(a) area under the curve between ± r limits is 0.5
(b) half of the observed values lie between ±r
limits

Two resistances 100Q±5Q and 150Q±15Q are connected in series. If the deviations are standard deviations, the resultant resistance can be expressed as :
(fl) 250 Q ± 20 Q (b) 250Q ± 10Q
(c) 250Q ±15.80 (d) 2500 ± 10.60
If the result of a measurement is expressed as X ± 3o where X – mean value and o = standard deviation, it means that:
(fl) approximately 99 percent of the readings lie between ± 3o limit
(b) 26 readings out of 1000 will lie outside ± delimit
(c) the odds for any readings to lie within ± delimit
(d) all of the above.
A batch of resistors have a mean value of 100.00. and a standard deviation e = 0.2 O. The probability corresponding to 2e is 0.9546. The value of odds that randomly selected resistor will lie within 100.00 ± 0.40 Q is :
(fl) 1 to 1 (b) 2.15 to 1
(c) 21 to 1 (d) 256 to 1.
According to Chauvenet’s criterion, a reading out of a set of n readings should be rejected if the probability of obtaining the particular deviation from mean is :
(fl) less than 1/2×2 (b) greater than l/2n
(c) less than 1/n (d) less than 1/ -J2n
If the confidence level is 0.95, then the values lying outside the confidence interval are :
(fl) 1 in 5 (b) 1 in 20
(c) 1 in 100 (d) 1 in 1000.
Uncertainty distribution is used for :
(a) analysis of multi-sample data
(b) analysis of single sample data
(c) analysis of both single and multi sample data
(d) none of the above.