100 TOP ELECTRONICS & INSTRUMENTATION Objective Questions and Answers pdf

ELECTRONICS & INSTRUMENTATION Objective Questions and Answers pdf free Download :-

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
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)


1. The decibel is a measure of
a) Current
b) Voltage
c) Power
d) Power level

Ans : (d)

2. Power gain in decibels is equal to voltage gain in decibels only when
a) Input impedance is equal to output impedance
b) Output impedance is zero
c) Never
d) Input impedance is zero

Ans : (a)

3. An ideal amplifier has
a) Noise figure of 0 db
b) Noise figure of more than 0 db
c) Noise factor of unity
d) Noise figure of less than 1 db
Ans : (c)

4. Fidelity represents
S1: Reproduction of signal
S2: Reproduction of phase relation
a) S1 and S2 are true
b) S1 and S2 are false
c) S1 false and S2 true
d) S1 true and S2 false
Ans : (d)

5. If the current gain of the amplifier is X, its voltage gain is Y, then its power gain will be
a) X/Y
b) X*Y
c) X+Y
d) X-Y

Ans : (b)

6. In an amplifier, the coupling capacitors are employed for
a) Limiting the bandwidth
b) Matching the impedance
c) Preventing of Dc mixing with input or output
d) Controlling the output

Ans : (c)

7. The amplifier which has no drift is called as
a) Differential amplifier
b) DC amplifier
c) Single ended amplifier
d) Chopper amplifier

Ans : (d)

8. The amplifier gain varies with frequency. This happens mainly due to
a) Miller effect
b) Presence of external and internal capacitance
c) Logarithmic increase in its output
d) Inter stage transformer

Ans : (b)

9. The outstanding characteristics of a D.C. amplifier is its
a) Ability to amplify Dc and low frequency signals
b) Temperature stability
c) Utmost economy
d) Avoidance of frequency sensitive components

Ans : (a)

10. Isolation amplifier actually operates on the principle of
a) Filtering
b) Attenuation
c) Clipping
d) Amplification
Ans : (b)

11. Isolation amplifiers are also called as
a) DC amplifier
b) Output amplifier
c) Inverting amplifier
d) Iso-amps

Ans : (d)

12. The improper response time of the amplifier in the biomedical recorders
a) Affects the gain of the amplifier
b) Delays the signals
c) Changes the shape of the waveform of the signal
d) Attenuates the signals

Ans : (c)

13. To reduce common mode interference during recording of bio signals one can use__________
a) Buffer amplifier
b) Differential amplifier
c) Single ended amplifier
d) Chopper amplifier

Ans : (b)

14. Resistively generated inference arises through incorrect __________________
a) Grounding
b) Current density at the electrodes
c) Supply voltage
d) Input impedance

Ans : (a)

15. CMRR is more in_______________
a) Single ended amplifier
b) Differential amplifier
c) Inverting operational amplifier
d) Chopper amplifier

Ans : (b)

16. For biomedical applications the mostly used amplifier is
a) Single ended amplifier
b) Differential amplifier
c) Inverting operational amplifier
d) Chopper amplifier
Ans : (b)

17. ___________ amplifier is used to drive the recorder.
a) Power amplifier
b) Pre amplifier
c) Operational amplifier
d) Differential amplifier

Ans : (a)

18. When a number of components are fabricated on same IC chip it is necessary to provide isolation between two different components for input interconnection is called __________
a) Input amplification
b) Input differentiation
c) Common mode rejection
d) Input isolation

Ans : (d)

19. A chopper amplifier
a) Converts AC signal from low frequency to high frequency
b) Converts DC signal from low frequency to high frequency
c) Converts AC signal from low frequency to DC high frequency
d) Converts DC signal from low frequency to high frequency

Ans : (b)

20. Power amplifier is provided with
S1: Cross over distortion compensation
S2: Offset control
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)

21. Pre amplifier isolation in ECG circuit is to
a) Increase input impedance
b) Decrease input impedance
c) Increase output impedance
d) Decrease output impedance

Ans : (a)

22. Raising input impedance of pre amplifier reduces
a) Input current
b) Output current
c) Stray current
d) Grid current

Ans : (c)

23. Common mode rejection ratio is defined as ratio of
a) Common mode gain to differential mode gain
b) Differential mode gain to common mode gain
c) Common mode gain at input to differential mode gain at input
d) Common mode gain at output to differential mode gain at output

Ans : (b)

24. An electrometer amplifier has high input impedance of
a) 1010?
b) 105?
c) 1020?
d) 1015?

Ans : (d)

25. When the input of differential amplifier V1 = 0, then the differential amplifier is said to be operated in
a) Common mode
b) Differential mode
c) Non inverting mode
d) Inverting mode

Ans : (c)

26. When either one of the inputs to the differential amplifier is equal to zero then it is said to be operated in
a) Single ended mode
b) Differential mode
c) Non inverting mode
d) Inverting mode

Ans : (a)
27. The negative feed back in an amplifier
a) Reduces voltage gain
b) Increases the voltage gain
c) Increases the gain band width product
d) Reduces the input impedances

Ans : (a)

28. Feedback in an amplifier always helps in
a) Increasing its input impedance
b) Increasing its gain
c) Controlling its output
d) Stabilizes its gain

Ans : (c)

29. Using mechanical chopper we cannot achieve high chopping rates due to their
a) Input impedance
b) Output impedance
c) Response time
d) Inertia

Ans : (d)

30. The CMRR of a typical IC OPAMP is
a) 70 dB
b) 80 dB
c) 85 dB
d) 75 dB

Ans : (b)

31. A ————– is usually a display device used to produce a paper record of analog wave form.
a) Graphic pen recorder
b) Electron microscope
c) X-Y recorder
d) Oscilloscope

Ans : (a)

32. The _________ of a recording system is the magnitude of input voltage required to produce a standard deflection in a recorded trace.
a) Accuracy
b) Linearity
c) Sensitivity
d) Resolution

Ans : (c)

33. A recorder is said to have good frequency response when the sensitivity of the system is _________ for all frequencies present in the signal.
a) Unity
b) Zero
c) Infinity
d) Constant

Ans : (d)

34. In phase response of a recorder noise level ___________ with the band width of a system
a) Increases
b) Decreases
c) Reaches unity
d) Reaches infinity

Ans : (a)

35. Function of microscope is
S1: To magnify object, under observation
S2: To resolve the object
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)

36. In electron microscope the projection of the motion on a plane normal to magnetic
induction (B) will be a circle of radius (r) =
a) mVsin?+eB
b) mVsin?/eB
c) mVsin?-eB
d) mVsin?*eB

Ans : (b)

37. Match the following
1. Electron microscope – (A) Electron gun
2. Oscilloscope – (B) Condensing magnetic lens
3. Galvanometric recorder – (C) Recording head
4. Magnetic recorder – (D) Drive motor
a) 1-A, 2-B, 3-C, 4-D
b) 1-D, 2-C, 3-B, 4-A
c) 1-B, 2-A, 3-D, 4-C
d) 1-C, 2-D, 3-A, 4-B

Ans : (c)

38. In PMMC writing system, the magnitude of pen deflection is proportional to
S1: Current flowing through the coil
S2: Voltage in the coil
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 : (a)

39. Duration of rotation of pen in the PMMC system depends upon ___________
a) Phase angle
b) Frequency
c) Magnitude
d) Direction

Ans : (d)

40. The shorter wave length of the electron permits the detailed examination of tiny objects due to reduction of ___________ effects
a) Reflection
b) Diffraction
c) Refraction
d) Polarization

Ans : (b)

41. Which of the following recorder gives slow response
a) X-Y recorder
b) Oscillographic
c) Galvanometric
d) Magnetic
Ans : (c)

42. The use of storage oscilloscope
S1: Viewing rapidly changing non repetitive wave forms
S2: Recording average values
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)

43. In X-Y recorders, the self balancing potentiometers plot emf as a function of
a) Another emf
b) Frequency
c) Time
d) Pressure
Ans : (a)

44. In strip chart recorders, the self balancing potentiometers plot emf as a function of
a) Another emf
b) Frequency
c) Time
d) Pressure

Ans : (c)

45. The slewing speed of X-Y recorder is
a) 1.6 m/s
b) 1.3 m/s
c) 1.4 m/s
d) 1.5 m/s

Ans : (d)

46. The resolution limit of electron microscope is
a) 2 A.V
b) 1 A.V
c) 1.5 A.V
d) 1.2 A.V

Ans : (b)

47. _____________ is also known as halftone storage or mersh storage.
a) Variable persistence storage
b) Bistable storage
c) Flat storage
d) CRT

Ans : (a)

48. Storage oscilloscope operates on the principle of
a) Primary emission
b) Deflection
c) Secondary emission
d) Diffusion

Ans : (c)

49. The writing speed of fast storage oscilloscope is
a) 2000 cm/?s
b) 1000 cm/?s
c) 1500 cm/?s
d) 2500 cm/?s

Ans : (a)

50. Stress and strain curves are plotted using
a) Magnetic tape recording
b) X-Y recording
c) Galvanometric
d) PMMC writing systems

Ans : (b)

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