sensor and transducers Important mcqs Questions for university exam 2021

Sensor and Transducers Important mcqs Questions for university exam & Interview

1) Which one of the following is passive transducer ?

A) Thermocouple. 
B) Strain gauge 
B) Thermopile 
D) Photovoltaic cell. 

2) Self generating type transducers are ……….. Transducers.

A) Active. 
B) passive 
C) secondary 
D) inverse.

3) Which one of the following is digital transducer ? 
a) Thermistor 
b) Encoder 
c) LVDT 
d) RTD.

4) LVDT can be used for 
a) Vibration measurement 
b) Angular velocity measurement 
c) Force measurement in a beam 
d) Load measurement on a column. 

5) The smallest change in input that a transducer can Sense is known as 
a) Sensitivity. 
b) resolution 
c) precision 
d) accuracy. 
6) Change in output of sensor with change in input is ____________ 
A) Threashold 
B) Slew rate 
C) Sensitivity 
D) None of the mentioned

7) The difference between the measured value and the true value is called 
A) Relative error 
B) Absolute error 
C) Probable error 
D) Gross error

8) The principle of operation of LVDT is based on variation of 
a) Self inductance 
c) mutual inductance
b) reluctance. 
D) permeance. 

9) Which of the following is an inverse transducer ? 
b) Load cell. 
c)Piezoelectric crystal. 
D) Radiation pyrometer. 

10) Residue voltage occurs due to 
a) Harmonics and stray capacitance 
b) Creeping error 
c) Hysteresis loss 
d) Eddy current loss 

11) Potentiometric resistance transducer measures __________ 
A) linear displacement 
B) rectangular displacement 
C) square displacement 
D) triangular displacement 

12) High value POT resistance leads to 
A) low sensitivity  
B) high sensitivity 
C) low non-linearity 
d) less error. 

13) Strain gauge is a 
A)Active device and converts mechanical displacement into a change of resistance 
B) Passive device and converts electrical displacement into a change of resistance 
C)Passive device and converts mechanical displacement into a change of resistance 
D) Active device and converts electrical displacement into a change of resistance  

14) Which of the following gives gauge factor of a strain Gauge ? 
(a) ( ∆L/L )/( ∆R/R ) 
(b) ( ∆R/R )/( ∆L/L ). 
(c) ( ∆R/R )/( ∆D/D ) 
(d) ( ∆R/R )/( ∆ρ/ρ ). 
15) The strain gauges should have low 
A) Gauge factor 
B) Resistance temperature coefficient 
C) Resistance 
D) All of these. 

16) Stress is defined as _________ 
A) diameter per unit area 
B) length per unit area 
C) weight per unit area 
D) force per unit area 

17) The sensitivity factor of strain gauge is normally of the order 
a) 1 to 1·5 
b) 1·5 to 2·0 
c) 0·5 to 1. 
d) 5 to 10. 

18) Dummy strain gauges are used for 
A) Calibration of strain gauges 
B) Compensation of temperature
C) Increasing bridge sensitivity
D) All of these 

19) Gauge factor of a strain gauge indicates its 
a) Accuracy 
b) Sensitivity 
c) Dead zone 
d) None of these 

20) Bonding element in a strain gauge must have __________ insulation resistance.
A) Zero 
b) low 
c) high 
d) infinite 

21) Commonly used elements for wire strain gauges are __________
A) nickel and copper 
B) nickel and gold 
C) gold and brass 
D) silver and aluminum

22) LVDT windings are wound on 
[a] Steel sheets. 
[b] Aluminium.
[c] Ferrite. 
[d] Copper 

23) Poisson’s ratio is given by which of the following relation? 
a) µ = –(Δd/d)/( Δl/l). 
b) µ = –Δd/(Δl/l) 
c) µ = –(Δd/d)/Δl. 
d) –( Δl/l)/(Δd/d) 

24) The gauge factor of semiconductor strain gauge is in the range of
(a) 2 to 10. 
(b) 100 to 150. 
(c) more than 200. 
(d) 50 to 100. 

25) Capacitive transducers are normally employed for Measurement of 
a) Static. 
b) dynamic 
c) Both (a) and (b) 
d) transient. 

26) Frequency response of capacitive transducers is ________ 
a) High 
b) medium
c) low 

27) Capacitive transducer displays _______ 
a) Linear behaviour 
b) Exponential behaviour
c)non-linear behaviour 
d) tangential behaviour

28) Capacitance of a parallel plate capacitor is ________ 
A) C = A∈⁄d 
B) C = ∈d/A 
C) C = A⁄d 
D) C = Ad/∈ 

29) Thermo-electric effect was first observed by 
a) Seebeck. 
B) Thomas Young 
c) Peltier 
d) Faraday.

30) The thermocouple circuit which is used to measure temperature works on ____. 
a) Seebeck effect
B) Peltier effect. 
C) Thomson effect. 
D) Joule effect 
31) How to protect the metals of thermocouple from the oxidation process ? 
a) Enclosed inside tubes 
c) Connect intermediate metal 
b) Keep on room temperature 
d) All are correct 

32) The series & parallel groups of thermocouples are called ________. 
a) Constantan 
b) Thermostat 
c) Thermopiles 
d) Thermistor 

33) Which of the following thermocouples will give the highest output for the same value of hot and cold junction temperature? 
A) Platinum-platinum + rhodium 
B) Chromel-constantan
C) Iron-constantan. 
D) All of the above 

34) Most suitable material for a thermocouple is ________ 
A) brass 
B) gold 
C) platinum 
D) silver 

35) For accurate temperature measurement in a thermocouple the __________ 
A) cold compensation is needed 
B) hot compensation is needed 
C) no compensation is needed 
D) hot and cold compensations are needed 

36) A thermocouple with reference junction temperature at 20˚C gives an output of 5 mV. If the thermocouple Sensitivity is 50 µV/˚C, the measured temperature is  
a) 100˚C 
b) 80˚C 
c) 120˚C. 
d) 250˚C. 

37) Electrical resistance of thermistor 
a) Increases as the temperature increases 
b) Decreases as the temperature increases 
c) Remains unaffected with the change in temperature 
d) Increases at low temperature and decreases at high temperature. 

38) Which of the following element is used as a thermocouple in nuclear reactor? 
A) Boron. 
B) Platinum 
C) Copper 

39) PTC thermistors are used in- 
A) Monitor fluid temperature in automotive applications 
B) Speed Measurements 
C) Digital thermostat 
D) Current limiting device for circuit protection 

40) Generally, the resistance of thermistor decreases _______ 
A) Linearly with an increase in temperature 
B) Linearly with the decrease in temperature 
C) Exponentially with an increase in temperature 
D) Exponentially with the decrease in temperature
41) In general the temperature coefficient of thermistor is 
a) Negative 
b) Positive 
c) Zero 
d) None of these 

42) A ________ is thermally sensitive resistor that exhibits a large change in resistance. 
A) Thermistor 
B) Thermo couple
C) Resistance Thermometer 
D) Semiconductor based sensor 

43) Which is not used to make RTD element? 
A) Copper.         
B) Platinum.           
C) Tungsten.          
D) Nickel 

44) Which is the most commonly used metal for RTD elements? 
A) Gold.     
B) copper.     
C) platinum.       
D) Silver 

45) Which sensor is linear and low accuracy? 
A)  Thermistor             
B)  Resistance Thermometer 
C) Thermocouple         
D) Semiconductor based sensor 

46) Quartz and Rochelle salt belong to 
a) Natural group       
b) Natural or Synthetic group                C) Synthetic group 
d) Fiber group 

47) A piezoelectric crystal has a voltage sensitivity of 2 MV/N. When a static force of 10 N is applied, then voltage generated in steady state- 
A) 2×10⁵ V                    
b) 2×10⁶ V                     
c)2×10⁷ V                  
d) 0 V

48) Piezoelectric effect is when materials produce electric charges when ____________ is applied. 
a) Electromotive force (EMF)                b)  Mechanical Stress  
c) Electric field                                        d) Magnetic field 

49) A piezoelectric transducers is a …….............. Transducers. 
A) Active.        
B) Passive.      
C) Inverse.      
D) Both (A) & (C) 

50) Angular or Rotatory sensor can best be realized by 
a) a modified version of LVDT 
b) a piezoelectric sensor 
c) a plunger in coil arrangement  
d) a stretched diaphragm sensor. 

51) An AD 590 sensor is generally used as 
a) A proportional to Absolute temperature ( PTAT )Sensor 
b) A magnetic flux sensor
c) A force transducer 
d) An accelerometer

 52) The temperature range of LM35 IC sensor is
a)  -45°C to 250°C.      
b) -150°C to 120°C.    
c) -55°C to 120°C.   
d) -45°C to 220°C  

53) The sensitivity of LM35 is. 
a) 10mV/°C.  
B) 10 uV/°C.     
C) 10 mV/K.      
D) 10 uV/K 

54) A platinum resistance thermometer has a resistance of 2 ohm at 0° C and 3 Ohm at 100° C. What will be the temperature when resistance indicates 5 ohm? 
a) 300° C        
b) 200° C.         
c) 350° C        
d)400° C 

55)  A quartz piezoelectric crystal having a thickness of 2 mm and voltage  Sensitivity of 0.055 V-m/N is subjected to a pressure of 1.5 MPa. The voltage Output will be-
a) 165 V.        
b) 175 V.           
c) 185 V.          
d) 195 V 

56)  A parallel plate air capacitors has plate area 0.2 m² and has separation distance 5.5 mm. Find its charge when a potential difference of 500 volts is  Applied on it. 
A) 0.3231 μC.             
B) 0.4425 μC.               
C) 0.1609 μC.        
D) 0.2495 μC

57) A transducer that converts measurand into the form of pulse is called- 
a)  Active transducer.      
b) Digital transducer    
C) Analog transducer     
D) Pulse tratransducer 

58) An inverse transducer is a device which converts 
a) An electrical quantity into a non electrical quantity 
b) Electrical quantity into mechanical quantity 
c) Electrical energy into thermal energy 
d) Electrical energy into light energy

59) When the number of turn in a coil is doubled without change in the physical parameters of the coil , its self inductance will be- 
a) Doubled. 
B) 4 times
C) ½ times. 
D) remain same 

60) Unit of reluctance is? 
a) AWb. 
B) A²/Wb 
C) Wb/A 
D) A/Wb 

61) Inductive proximity sensors can be effective only when the objects are of _____ materials. 
a) Ferro magnetic 
B) Diamagnetic 
C) Paramagnetic 
D) All of the above

62) Following type of sensors are used to generate information in object grasping and obstacle avoidance. 
a) Hall Effect sensor 
B) Proximity sensor 
C) Light sensor. 
D) Optical sensors 
63) Hall effect transducers are used for measuring 
a) Magnetic field 
B) Temperature 
C) Electric field 
D) pressure. 

64) Force exerted by magnetic field in Hall Effect transducers is ____________ 
A) Lorentz force 
B) Hall Effect force 
C) Magnetic force 
D) Electric force 

65) Which of the following represents correct expression for Lorentz force? 
A) BeV 
B) BV 
C) eV 
D) B 

66) Hall Effect is clearly visible in _______________ 
A) Pure conductors 
B) Semiconductors 
C) Super conductors 
D) Metals 

67) Hall Effect transducer can be used to measure ___________ 
a) Magnetic field 
b) Linear displacement 
c) Angular displacement 
d) All of the mentioned 

68) Which of the following acts as ionising gas in Geiger Muller counter?
a) Alcohol 
B) Argon gas 
C) Krypton. 
D) Hydrogen

69) Which of the following acts as quenching gas in Geiger Muller counter? 
A) Alcohol 
B) Argon gas 
C) Krypton 
D) Hydrogen

70) Scintillation detector is a large flat crystal of which of the following materials? 
a) Sodium chloride 
b) Sodium sulphate 
c) Sodium iodide 
d) Sodium carbonate 

71) Any radiation of appropriate wavelength fall on the depletion layer of p-n junction develops a potential difference between the junction is working principle of 
A) Hall Effect sensor. 
B) Proximity sensor. 
C)Light sensor 
D) All of the above

72) Following is (are) the type(s) of Light sensor(s) 
a) Photo sensor 
B) Photo transistors 
C) Photo conductors 
D) All of the above

73) What is the use of the LDR Sensor? 
a) Monitors Motion 
b) Monitors Light Intensity 
c) Monitors air pressure 
d) Monitors heartbeat
74) Following acts as detector in Optical sensor 
A) Light emitting diode. 
B) Photo diode 
C) Transistor 
D)All of the above 

75) are also called _______________
a) Photo voltaic cell 
b) Photo emissive cell 
c) Photo resistive cell or light dependent resistor 
d) All of the mentioned 

76) With the increase in the intensity of light, the resistance of a photovoltaic cell 
A) Increases. 
B) Decreases. 
C) Remains same. 
D) None of these 

77) Photo resistive cells are _____________ 
A) Active device 
B) Passive device 
C) Insulating device
D) None 

78) Which of the following materials can be used as photoconductive transducer? 
a) Selenium.
B) Silicon 
C) Germanium 
D) All of the mentioned

79) Which one of the following materials would be used for making an LDR? 
a) Lead Sulfide
b) Sodium sulphate
c) Aluminium oxide.
d) Copper telluride 

80) Which is most commonly used materials for making an LDR? 
A)Cadmium Sulfide
B) Pure Aluminum
C) Iron Ore
D) Aluminum Oxide 

81) Photo-diodes work in _________ 
A) forward biased  
B) independent of forward and reverse biasing
C) reverse biased
D) any configuration 

82) Photo conductive cell consists of a thin film of 
a) Quartz 
B) Lithium sulphate 
C) Barium titanate 
D) Selenium 

83) The types of solar cells based on the crystal structure of silicon are _________ 
A) Single crystal 
B) Polycrystalline
C) Amorphous 
D) All of the above 

84) The most suitable device for measuring temperature of Furnace is 
C)Optical pyrometer 
D)Bimetallic thermometer. 

85) Radiation pyrometers are used in temperature range of 
A) 0 to 500°C 
B)500 to 1000°C
C)– 250 to 500°C
D) 1200 to 3000°C. 

86) In optical pyrometers temperature is measured by 
a) The thermocouple effect
b) Comparison of brightness of the object with that of Stand ard source
c) Photocell principle
d) None of these.

87) Which of the following effect is Converse of magnetostriction effect? 
A) Skin effect.
B) Doppler effect.
C) Curie effect.
D) Villari effect. 

88) What is the use of the Ultrasonic Sensors 
A) Proximity Detection
B) Humidity Detection
C) Image Processing

89) Load cell is a transducer which measures
A) Force
B) temperature
D) pressure.

90) The transducer used in weighing machine is-
B) load cell.
C) capacitive transducers.
D) Piezoelectric sensor

91) Angular velocity is measured by 
A) Strain gauge
B) Solar cell
C) A.C. tacho-generator

92) RVDT(Rotary variable differential transformer) is used to measure 
a) Angular displacement.
b) Linear displacement.
C) Angular velocity
D) linear velocity 

93) Venturi meter transducer works on the principle of 
a) Pressure difference between two points of flowing Fluid
b) Temperature difference in two points in fluid
c) Resistance change in fluid flow
d) Electrical potential gradient between two points in Flow line.

94) Output of smart sensors will of ________________ 
A) Analog
B) Digital.
C) Analog and digital
D) None 

95) Which of the following is correct for tactile sensors? 
a) Touch sensitive.
b) Input voltage sensitive
c) Pressure sensitive
d) Humidity sensitive 

96) Touch screen of mobile phone uses: 
a) AFR Sensor
b) Pellistor
d) Tactile sensors ( If not in option then capacitive touch sensor) 

97) Which of the following can be cause for non-zero output when zero input? 
A) Bias
B) Slew
C) Offset
D) Offset or bias 

98) Sensitivity of a sensor can be depicted by _______________ 
a) Niquist plot
B) Pole- zero plot
C) Bode plot
D) None of the mentioned 

99) Following is not an example of transducer
a) Analog voltmeter.
C) Thermocouple
b) Photo electric cell
D) Pnuematic cylinder

100) The ability to give same output reading when same input value is applied is known as 
a) Stability.
B) Repeatability.
C) Accuracy
D) Sensitivity 

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