## electrical

### Electrical Instruments MCQ Objective Questions and Answers Page - 2

1.
 In a 3-phase power measurement by two wattmeter method, both the wattmeters had identical readings. The power factor of the load was A Unity B 0.8 lagging C 0.8 leading D Zero Answer : A Explanation :
2.
 In a 3-phase power measurement by two wattmeter method the reading of one of the wattmeter was zero. The power factor of the load must be A Unity B 0.5 C 0.3 D Zero Answer : B Explanation :
3.
 The adjustment of position of shading bands, in an energy meter is done to provide A Friction compensation B Creep compensation C Braking torque D None of the above Answer : A Explanation :
4.
 An ohmmeter is a A Moving iron instrument B Moving coil instrument C Dynamometer instrument D None of the above Answer : B Explanation :
5.
 For measuring a very high resistance we should use A Kelvin’s double bridge B Wheat stone bridge C Meggar D None of the above Answer : C Explanation :
6.
 The electrical power to a megger is provided by A Battery B Permanent magnet DC generator C AC generator D Any of the above Answer : B Explanation :
7.
 In a megger controlling torque is provided by A Spring B Gravity C Coil D Eddy current Answer : C Explanation :
8.
 The operating voltage of a megger is about A 6 V B 12 V C 40 V D 100 V Answer : D Explanation :
9.
 Murray loop test can be used for location of A Ground fault on a cable B Short circuit fault on a cable C Both the ground fault and the short circuit fault D None of the above Answer : C Explanation :
10.
 Which of the following devices should be used for accurate measurement of low DC voltage? A Small range moving coil voltmeter B DC potentiometer C Small range thermocouple voltmeter D None of the above Answer : B Explanation :
11.
 It is required to measure the true open circuit emf of a battery. The best device is A DC voltmeter B Ammeter and a known resistance C DC potentiometer D None of the above Answer : C Explanation :
12.
 A voltage of about  200 V  can be measured A Directly by a DC potentiometer B A  DC potentiometer in conjunction with a volt ratio box C A  DC potentiometer in conjunction with a known resistance D None of the above Answer : B Explanation :
13.
 A direct current can be measured by A A  DC  potentiometer directly B A  DC potentiometer in conjunction with a standard resistance C A  DC potentiometer in conjunction with a volt ratio box D None of the above Answer : B Explanation :
14.
 To measure a resistance with the help of a potentiometer it is A Necessary to standardise the potentiometer B Not necessary to standardise the potentiometer C Necessary to use a volt ratio box in conjunction with the potentiometer D None of the above Answer : B Explanation :
15.
 A phase shifting transformer is used in conjunction with A DC potentiometer B Drysdale potentiometer C AC co-ordinate potentiometer D Crompton potentiometer Answer : B Explanation :
16.
 Basically a potentiometer is a device for A Comparing two voltages B Measuring a current C Comparing two currents D Measuring a voltage Answer : A Explanation :
17.
 In order to achieve high accuracy, the slide wire of a potentiometer should be A As long as possible B As short as possible C Neither too small not too large D Very thick Answer : A Explanation :
18.
 The stator of phase shifting transformer for use in conjunction with an AC potentiometer usually has a A Single-phase winding B Two-phase winding C Three-phase winding D Any of the above Answer : B Explanation :
19.
 In an AC co-ordinate potentiometer, the currents in the phase and quadrature potentiometer are adjusted to be A Out of phase by 900 B Out of phase by 600 C Out of phase by 300 D Out of phase by 00 Answer : A Explanation :
20.
 For measurements on high voltage capacitors, the suitable bridge is A Wein bridge B Modified De Santy’s bridge C Schering bridge D Any of the above Answer : C Explanation :
21.
 In an Anderson bridge, the unknown conductance is measured in terms of A Known inductance and resistance B Known capacitance and resistance C Known resistance D Known inductance Answer : B Explanation :
22.
 Wagner earthing device is used to eliminate errors due to A Electrostatic coupling B Electromagnetic coupling C Both (a) and (b) D None of the above Answer : A Explanation :
23.
 For measurement of mutual inductance we can use A Anderson bridge B Maxwell’s bridge C Heaviside bridge D Any of the above Answer : C Explanation :
24.
 For measurement of inductance having high value, we should use A Maxwell’s bridge B Maxwell Wein bridge C Hay’s bridge D Any of the above Answer : C Explanation :
25.
 If the current in a capacitor leads the voltage by  800, the loss angle of the capacitor is A 100 B 800 C 1200 D 1700 Answer : A Explanation :
26.
 In a Schering bridge the potential of the detector above earth potential is A A few volts only B 1 kV C 5 kV D 10 kV Answer : A Explanation :
27.
 To avoid the effect of stray magnetic field in AC bridges we can use A Magnetic screening B Wagner earthing device C Wave filters D Any of the above Answer : A Explanation :
28.
 If an inductance is connected in one arm of bridge and resistances in the remaining three arms A The bridge can always be balanced B The bridge cannot be balanced C The bridge can be balanced if the resistances have some specific values D None of the above Answer : B Explanation :
29.
 A power factor meter has A One current circuit and two pressure circuits B One current circuit and one pressure circuit C Two current circuits and one pressure circuit D None of the above Answer : A Explanation :
30.
 The two pressure coils of a single phase power factor meter have A The same dimensions and the same number of turns B The same dimension but different number of turns C The same number of turns but different dimensions D None of the above Answer : A Explanation :
31.
 In a single phase power factor meter the phase difference between the currents in the two pressure coils is A Exactly 00 B Approximately 00 C Exactly 900 D Approximately 900 Answer : C Explanation :
32.
 In a dynamometer 3-phase power factor meter, the planes of the two moving coils are at A 00 B 600 C 900 D 1200 Answer : D Explanation :
33.
 In a vibrating reed frequency meter the natural frequencies of two adjacent reeds have a difference of A 0.1 Hz B 0.25 Hz C 0.5 Hz D 1.5 Hz Answer : C Explanation :
34.
 On a Weston frequency meter, the magnetic axes of the two fixed coils are A Parallel B Perpendicular C Inclined at 600 D Inclined at 1200 Answer : B Explanation :
35.
 A Weston frequency meter is A Moving coil instrument B Moving iron instrument C Dynamometer instrument D None of the above Answer : B Explanation :
36.
 A Weston synchronoscope is a A Moving coil instrument B Moving iron instrument C Dynamometer instrument D None of the above Answer : C Explanation :
37.
 In a Weston synchronoscope, the fixed coils are connected across A Bus-bar B Incoming alternator C A lamp D None of the above Answer : B Explanation :
38.
 In Weston synchronoscope, the moving coil is connected across A Bus-bar B Incoming alternator C Fixed coils D Any of the above Answer : A Explanation :