ELECTRONICS & INSTRUMENTATION QUESTIONS

1. Self generating type transducers are ___________ transducers.
a) Active
b) Passive
c) Secondary
d) Inverse
Ans : (a)

2. The transducers that converts the input signal into the output signal, which is a discrete function of time is known as ___________ transducer.
a) Active
b) Analog
c) Digital
d) Pulse
Ans : (c)

3. A transducer that converts measurand into the form of pulse is called
a) Active transducer
b) Analog transducer
c) Digital transducer
d) Pulse transducer
Ans : (d)

4. Which of the following is a digital transducer?
a) Strain gauge
b) Encoder
c) Thermistor
d) LVDT
Ans : (b)

5. Strain gauge, LVDT and thermocouple are examples of
a) Active transducers
b) Passive transducers
c) Analog transducers
d) Primary transducers
Ans : (c)

6. 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
Ans : (a)

7. A strain gauge is a passive transducer and is employed for converting
a) Mechanical displacement into a change of resistance
b) Pressure into a change of resistance
c) Force into a displacement
d) Pressure into displacement
Ans : (a)

8. Resolution of a transducer depends on
a) Material of wire
b) Length of wire
c) Diameter of wire
d) Excitation voltage
Ans : (c)

9. The sensitivity factor of strain gauge is normally of the order of
a) 1 to 1.5
b) 1.5 to 2.0
c) 0.5 to 1.0
d) 5 to 10
Ans : (b)

10. In wire wound strain gauges, the change in resistance is due to
a) Change in diameter of the wire
b) Change in length of the wire
c) Change in both length and diameter
d) Change in resistivity
Ans : (c)

11. Bonded wire strain gauges are
a) Exclusively used for construction of transducers
b) Exclusively used for stress analysis
c) Used for both stress analysis and construction of transducer
d) Pressure measurement
Ans : (c)

12. Certain type of materials generates an electrostatic charge or voltage when mechanical force is applied across them. Such materials are called
a) Piezo-electric
b) Photo-electric
c) Thermo-electric
d) Photo-resistive
Ans : (a)

13. Quartz and Rochelle salt belongs to ___________ of piezo-electric materials
a) Natural group
b) Synthetic group
c) Natural or Synthetic group
d) Fiber group
Ans : (a)

14. Which of the following are piezo electric substances?
1. Barium titanate
2. Lead titanate
3. Lead Zirconate
4. Cadmium and sulphate
a) 1,2 and 4
b) 1,3and4
c) 1,2and 3
d) 2,3and 4
Ans : (c)

15. Piezo-electric transducers are
a) Passive transducers
b) Inverse transducers
c) Digital transducers
d) Pulse transducers
Ans : (b)

16. Piezo – electric transducers work when we apply _____________ to it.
a) Mechanical force
b) Vibrations
c) Illuminations
d) Heat
Ans : (d)
17. Piezo electric crystal can produce an emf
a) When external mechanical force is applied to i
b) When radiant energy stimulates the crystal
c) When external magnetic field is applied
d) When the junction of two such crystals are heated
Ans : (a)

18. The draw backs of strain gauges are
S1: Low fatigue life
S2: They are expensive, brittle and sensitive to temperature
S3: Poor linearity
a) S1 and S2
b) S2 and S3
c) S1 and S3
d) S1 only
Ans : (b)

19. LVDT windings are wound on
a) Steel sheets
b) Aluminium
c) Ferrite
d) Copper
Ans : (c)

20. The size of air cored transducers in comparison to the iron core parts is
a) Smaller
b) Larger
c) Same
d) Unpredictable
Ans : (b)

21. The principle of operation of LVDT is based on the variation of
a) Self inductance
b) Mutual inductance
c) Reluctance
d) Permanence
Ans : (b)

22. LVDT is an/a ___________ transducer
a) Magneto-strict ion
b) Inductive
c) Resistive
d) Eddy current
Ans : (d)

23. Which of the following can be measured with the help of piezo electric crystal?
a) Force
b) Velocity
c) Sound
d) Pressure
Ans : (a)

24. S1: Transducer is a device which converts physical into electrical quantity
S2: Transducer is also called as sensor.
a) S1 is true & S2 is false
b) S2 is true & S1 is false
c) Both S1 & S2 are true
d) Both S1 & S2 are false
Ans (b)

27. In a LVDT, the two secondary voltages
a) Are independent of the core position
b) Vary unequally depending on the core position
c) Vary equally depending on the core position
d) Are always in phase quadrature
Ans : (b)

28. Capacitive transducers are normally employed for___________ measurements
a) Static
b) Dynamic
c) Transient
d) Both static and dynamic
Ans : (b)

29. Match the following
1. EEG A. Diagnostic tool for heart alignment
2. ECG B. Diagnostic tool for brain alignment
3. Sphygmo-manometer C. Instrument used for measuring blood pressure
4. Stethoscope D. instrument used to hear pulse/heart beat
a) 1- B, 2 – A, 3 – C, 4 – D
b) 1 – B, 2 – A, 3 – D, 4 – C
c) 1- C, 2 – A, 3 – B, 4 – D
d) 1 – A, 2 – B, 3 – C, 4 – D
Ans : (a)

30. Pick the correct statement regarding functions of a transducer
S1: Sense the magnitude, change in & / or frequency of same measurand
S2: To provide electrical output that furnishes accurate, quantitative data about the measurand
a) S1 is true & S2 is false
b) S2 is true & S1 is false
c) Both S1 & S2 are true
d) Both S1 & S2 are false
Ans : (c)

31. The transducers which requires an external power and their output is a measure of some variation such as resistance, inductance, capacitance etc., are called as
a) Active transducer
b) Primary sensor
c) Passive transducer
d) Self generating transducer
Ans : (c)

32. The principle of operation of variable resistance transducer is
a) Deformation leads to change in resistance
b) Displacement of a contact slider on a resistance
c) Coupling of two coils changes with displacement
d) Movement of magnetic field produces variation in resistance of material
Ans : (b)

33. The application of LVDT is
a) Joint motion
b) Finger movement
c) Limb movement
d) Heart wall motion
Ans : (c)

34. Venturi is associated with
a) Venous blood pressure
b) Digital plethysmography
c) Dialysate flow in artificial kidney
d) Blood flow in heart lung machine
Ans : (d)

35. Pressure transducer for measuring blood pressure is
a) Strain gauge transducer only
b) Strain gauge or capacitive transducer
c) Resistive transducer
d) Fiber optic transducer
Ans : (b)

36. The change in resistance of a metal wire owing to strain is due to
S1: Change in dimension of wire expressed by factor (1-2µ)
S2: Change in resistance ??
a) S1 is true & S2 is false
b) S2 is true & S1 is false
c) Both S1 & S2 are true
d) Both S1 & S2 are false
Ans : (b)

37. In foil strain gauge the thickness of foil varies from
a) 2.5 micron to 6 micron
b) 25 micron (or) less
c) 25 micron to 60 micron
d) 2.5 micron to 5 micron
Ans : (a)
38. Photo conductive cell consists of a thin film of
a) Quartz
b) Lithium sulphate
c) Barium titanate
d) Selenium
Ans : (d)

39. S1: In multimode fiber optics, intensity modulating schemes can be employed.
S2: Schemes using polarizing techniques need birefringent fiber.
a) S1 is true and S2 is false
b) Both S1 and S2 are true
c) S1 is false and S2 is true
d) Both S1 and S2 are false
ans (b)

40. Test electrode is also known as
a) Indicator electrode
b) Reference electrode
c) Second electrode
d) Primary electrode
Ans : (a)

41. Most commonly used indicator electrode is
a) Calomel electrode
b) Silver electrode
c) Silver – Silver chloride electrode
d) Glass electrode
Ans : (d)

42. _____________ is the example of photo emissive cell
a) LDR
b) Photo diode
c) Photo transistor
d) Photo multiplier
Ans : (a)

43. pH value of venous blood is
a) 7.30
b) 7.40
c) 7.35
d) 7.45
Ans : (c)

44. Silver chloride electrode is used as a reference electrode due to its
a) Large half cell potential
b) Stable half cell potential
c) Stable resting potential
d) Stable action potential
Ans : (b)

45. The capacitance microphone is used for the detection of
a) Heart rate
b) Blood flow
c) Heart sound
d) Foot pressure
Ans : (c)
46. In a graded index fiber, the total reflected light takes a ___________
a) Straight line path
b) Parabolic path
c) Elliptical path
d) Circular path
Ans (b)

47. ____________ fiber is used in interferometric instruments.
a) Monomode
b) Multimode
c) Birefringent
d) Coated
Ans (a)

48. Fiber optic sensor can be used to sense _________
a) Displacement
b) Power
c) Current
d) Resistance
Ans (a)

49. Photo multiplier consists of
a) 1 Photo emissive cathode & 2 dynodes
b) 2 Photo emissive cathodes & 2 dynodes
c) 2 Photo emissive cathodes & 1 dynode
d) 1 Photo emissive cathode & 1 dynode
Ans : (a)

50. The resistance of LDR ________________ when exposed to radiant energy.
a) Remains unaltered
b) Increases
c) Reaches maximum
d) Decreases
Ans : (d)