## electrical

### Electrical Instruments MCQ Objective Questions and Answers Page - 1

1.
 In a generalised measurement system the function of the signal manipulating element is to A Change the quantity under measurement to an analogous signal. B Change the magnitude of the input signal while retaining its identity. C Perform linear operations like addition and multiplication. D Perform linear operations like addition and multiplication. Answer : C Explanation :
2.
 A recorder A Is an indicating instrument which displays a time varying signal. B Is a device whose function is to record the value of quantity as it is being measured. C Records electrical and non-electrical quantities as a function of time or relates two signals to each other. D Both (b) and (c) Answer : D Explanation :
3.
 Strip-chart recorders have the advantage(s) of A Long period run B More actually usable width C Possibility of change in chart speed simply by lever actions. D All of the above Answer : D Explanation :
4.
 The zero-suppression in recorders implies A Recording signals with reference to a point other than the zero. B Removing the static component so that rest of the signal is displayed with more expansion. C Providing inertia-less components to improve transient response. D Designing  the recorder for zero error. Answer : B Explanation :
5.
 Galvanometer type recorders use A Vibration Galvanometer B Ballistic Galvanometer C D’Arsonval Galvanometer D Tangent Galvanometer Answer : C Explanation :
6.
 Galvanometer used in recorders is A An ordinary D’Arsonval Galvanometer. B Somewhat different from the ordinary D’Arsonval Galvanometer. C A D’Arsonval Galvanometer with large moving coil, strong magnetic field and critical damping. D Both (b) and (c) Answer : D Explanation :
7.
 The potentiometric recorders have the advantage(s) of A Very high input impedance. B High sensitivity. C High response to rapidly changing quantities. D Both (a) and (b) Answer : D Explanation :
8.
 The main drawback of balancing recorders is that A Their ability to respond to rapidly changing quantities is quite limited. B Low input impedance C Low input sensitivity D None of these Answer : A Explanation :
9.
 The advantage of  x – y recorders are that A They are economical to operate. B They are easy and convenient to use. C They are cheaper than strip-chart recorders. D Both (a) and (b) Answer : D Explanation :
10.
 The recording head in a magnetic tape responds to A Electrical signal and creates a magnetic signal. B Thermal signal and creates a magnetic signal. C Magnetic signal and creates an electrical signal. D Thermal signal and creates an electrical signal. Answer : A Explanation :
11.
 The main drawback of direct recording is A Complicated circuitry B Poor signal-to-noise ratio C Poor reliability D Limited high frequency response Answer : B Explanation :
12.
 The advantage of  FM  magnetic tape recording are A It can record from dc to several kHz. B It is free from dropout effects. C It is independent of amplitude variations and reproduces the waveform of the input signal accurately. D All of the above. Answer : D Explanation :
13.
 The digital tape recording has the advantage(s) of A Giving highly accurate results B Insensitivity to speed of tape C Need a simple data conditioner D All of the above Answer : D Explanation :
14.
 Continuous recording of a signal is not possible in a A Magnetic tape recorder B Strip chart recorder C X-Y recorder D Galvanometric recorder Answer : D Explanation :
15.
 Which one of the following statements is not correct  ? A Data loggers are usually of digital types. B A digital voltmeter is essentially an A-D converter. C A servo-type potentiometric recorder has a frequency response better than of a galvanometric recorder. D In digital transducers, there are ergonomic advantages in presenting digital data. Answer : C Explanation :
16.
 Which one of the following instruments is most suitable to study the behaviour of a damped transient around  10 kHz  ? A Double beam  CRO B Recorder C Storage Oscilloscope D Plotter Answer : B Explanation :
17.
 The instrument servomechanism is actually an instrument system made of components,  which are A Exclusively passive transducers. B Exclusively active transducers. C Combination of passive transducers and active transducers. D Exclusively primary sensing elements. Answer : C Explanation :
18.
 A common element in most of the instrumentation systems for reasons of its compactness and linearity in its characteristics is A Cantilever beams B Helical spiral springs C Load cells D Torsion bars Answer : B Explanation :
19.
 The limitation of bellow element application to measurement is due to their lack of A Flexural rigidity B Low spring rate C Zero stability D Flexibility Answer : B Explanation :
20.
 Pitot tubes are used for A Industrial applications B Laboratory experimental purposes C Both Industrial and Laboratory applications D None of the above Answer : C Explanation :
21.
 If the number of bellows elements is made double and the thickness of the bellows element is made half, the displacement of the element for the same applied pressure would be the A 16 times B 4 times C Same D One-fourth Answer : A Explanation :
22.
 A rotameter works on the principle of variable  : A Pressure B Length C Area D Resistance Answer : C Explanation :
23.
 A diaphragm has a natural frequency of  30 kHz. If both its diameter and thickness are halved, the natural frequency is A 15 kHz B 240 kHz C 60 kHz D 120 kHz Answer : C Explanation :
24.
 The instrumentation amplifiers are used principally to amplify signals from which of the following  ? A Transducers B Active flitters C Choppers D D/A converters Answer : A Explanation :
25.
 Which one of the following in simple elemental forms is not a pressure sensor  ? A Cantilever beam B Bourdon tube C Diaphragm D Bellows Answer : A Explanation :
26.
 An inverse transducer converts A Electrical energy to ant other form of energy B Electrical energy to light energy C Mechanical displacement into electrical signal D Electrical energy to mechanical form Answer : A Explanation :
27.
 Transducers that are based on the variation of parameters due to application of any external stimulus are known as A Resistive transducers B Active transducers C Passive transducers D Displacement transducers Answer : B Explanation :
28.
 Self-generating type transducers are  ____________  transducers. A Active B Passive C Secondary D Inverse Answer : A Explanation :
29.
 Which one of the following is  not  a self-generating type transducers  ? A Thermocouple and thermopile B Piezoelectric pick-up C Photovoltaic cell D Magnetostriction gauge Answer : D Explanation :
30.
 Which one of the following is a passive transducer  ? A Piezoelectric B Thermocouple C Photovoltaic cell D LVDT Answer : D Explanation :
31.
 Which one of the following transducers is an active transducer  ? A Piezoelectric pressure transducer B Metallic strain gauge C Semiconductor strain gauge D Platinum resistance thermometer Answer : A Explanation :
32.
 Which of the following transducers is classified as an active transducer  ? A Metallic strain gauge B Capacitive microphone C LVDT D Piezoelectric transducer Answer : D Explanation :
33.
 Pair of active transducers is A Thermistor, Solar cell B Thermocouple, Thermistor C Thermocouple, Solar cell D Solar cell, LVDT Answer : C Explanation :
34.
 Which of the following can act as an inverse transducer  ? A LVDT B Strain Gauge C Piezo electric crystal D Bimetal strip Answer : C Explanation :
35.
 The lower limit of useful working range of a transducer is determined by A Minimum useful input level B Transducer error and noise C Cross-sensitivity D Dynamic response Answer : B Explanation :
36.
 An ac signal conditioning is normally used for A Resistive transducers like strain gauge B Inductive and capacitive transducers C Piezoelectric transducers D All of the above Answer : B Explanation :
37.
 While selecting a transducer for a particular application, only A Input characteristics should be considered. B Output characteristics should be considered. C Transfer characteristics should be considered. D Input, output and transfer characteristics should be considered. Answer : D Explanation :
38.
 In a resistance potentiometer, the nonlinearity A Decreases with the increase in ratio of potentiometer to load resistance. B Increases with the increase in ratio of potentiometer to load resistance. C Is independent of potentiometer to load resistance. D None of the above. Answer : B Explanation :
39.
 In hygrometers the principle of measurement is A Change in resistance of salts with humidity B Change in microwave power using klystron C Change in thermal conductivity using thermistor D None of the above Answer : A Explanation :