Linear Integrated Circuit MCQ [Free PDF] – Objective Question Answer for Linear Integrated Circuit Quiz

41. What instrument is used to amplify the output signal of the transducer

A. Peaking amplifier
B. Instrumentation amplifier
C. Differential amplifier
D. Bridge amplifier

Answer: B

The major function of the instrumentation amplifier is to amplify the low-level output signal of the transducer so that it can drive the output stages.


42. General purpose op-amps are used in applications as

A. Instrumentation amplifier
B. Differential instrumentation amplifier
C. Inverting instrumentation amplifier
D. Non-inverting instrumentation amplifier

Answer: B

When the requirement for the application is not too strict. The general purpose op-amp can be employed in the differential mode. Such amplifiers are called Differential instrumentation amplifiers.


43. In an instrumentation amplifier using a transducer bridge, which device measures the change in physical energy

A. Resistive transducer
B. Indicating meter
C. Capacitive transducer
D. Inductor circuit

Answer: A

A resistive transducer is used to measure the change in the same physical energy, which is connected to one arm of the bridge.


44. The temperature of a thermistor increases, when the value of its resistance

A. Remain constant
B. Increase
C. Decrease
D. Depends on the heating material

Answer: C

The thermistor is a semiconductor that behaves like a resistor, with a negative temperature coefficient of resistance. As the temperature of the thermistor increases, its resistance decreases.


45. Consider the entire resistors in the bridge circuit are equal. The resistance and change in resistance are given as 3kΩ and 30kΩ. Calculate the output voltage of the differential instrumentation amplifier?

A. 4.95v
B. 1.65v
C. 8.25v
D. 14.85v

Answer: B

The output voltage of the circuit is

Vo =-(RF/R1)×(△R/R)×Vdc

= (5.5kΩ/100Ω)×(30kΩ/3kΩ)×3 = 1.65v.


46. Consider a thermistor having the following specifications: RF=150kΩ at a reference temperature of 35oC and temperature coefficient of resistance = 25oC. Determine the change in resistance at 100oC.

A. -1.625MΩ
B. 9.75MΩ
C. 4.78MΩ
D. None of the mentioned

Answer: A

Thermistor has a negative temperature coefficient of resistance.

Therefore, △R=-(25kΩ/oC )×(100oC-35oC. = -1625kΩ .



47. Consider the given bridge circuit, and find the voltage across the output terminal, Vab.

Consider the given bridge circuit, find the voltage across the output terminal, Vab.

A. Vab = 4.9v
B. Vab = -5.6v
C. Vab =1.2v
D. Vab =-8.2v

Answer: A

According to the voltage divider rule,

Va =( Ra×Vdc)/[Ra+(RT+△R)]

= (1kΩ×5v)/(1kΩ+75kΩ) = 0.065v

Vb = ( Rb×Vdc)/(Rb+Rc)

= (50kΩ×5v)/(50kΩ+250Ω) = 4.975v

The voltage across the output terminal of the bridge, Vab = Va– Vb = 4.9v.


48. Express the equation for the transducer bridge, if all the resistor values are equal

A. v=-(△R×Vdc)/(2×R+△R)
B. v=-(△R×Vdc)/2×(R+△R)
C. v=-Vdc/[2×(2×R+△R)].
D. v=-(△R×Vdc)/ [2×(2×R+△R)].

Answer: D

If the Ra=Rb=Rc=RT=R(Equal), then the output voltage across the bridge terminals of the transducer bridge is

v=-(△R×Vdc)/ [2×(2×R+△R)].


49. Which type of thermistor is chosen for temperature measurement and control?

A. High-temperature coefficient of resistance
B. Low-temperature coefficient of resistance
C. Positive temperature coefficient of resistance
D. None of the mentioned

Answer: A

Thermistors with a high-temperature coefficient resistance are more sensitive to temperature change and are therefore well suited to temperature measurement and control.


50. Photoconductive cell changes its resistance with

A. Change in temperature
B. Material composition
C. Incident radiant energy
D. Change in elasticity

Answer: C

The photoconductive cell is a type of transducer that changes its resistance or varies its resistance with an incident radiant energy with light.


51. What will be the resistance of a photoconductive cell in darkness?

A. 1000-3000Ω
B. 100MΩ
C. 250-500Ω
D. None of the mentioned

Answer: D

The resistance of the photoconductive cell in darkness is typically in the order of 100kΩ.


52. Which material is used for photoconductive cells?

A. Germanium
B. Cadmium sulfide
C. Lithium
D. Phosphorous

Answer: B

The conductivity in cadmium sulfide is a function of incident radiant energy. So, it is used for the photoconductive cell.


53. Name the resistive transducer that varies its resistance on the application of external stress?

A. Photocells
B. Light-dependent
C. Stain gage
D. None of the mentioned

Answer: C

The strain gage is a type of resistive transducer whose resistance changes due to elongation or compression when the external stress is applied.


54. Strain gage are used to monitor changes in

A. Pressure
B. Torque
C. Displacement
D. All of the mentioned

Answer: D

A strain gage may be used to monitor changes in applied pressure, torque, and displacement by measuring the corresponding change in the gage resistance.


55. Which type of resistive transducer is most commonly used?

A. Thermistor
B. Photoconductive cell
C. Strain gage
D. All of the mentioned

Answer: A

Thermistors are most commonly used because they are relatively easy to mount.


56. What is the unit of strain gauge?

A. Ω/oC
B. Lux
C. Newton / meter2
D. Volts

Answer: C

The strain gauge changes resistance when the external stress is applied. Therefore, the stress is defined as force/unit area i.e. Newton/meter2.


57. Which type of strain gauge has a better resolution?

A. Semiconductor strain gage
B. Wire strain gage
C. Wire and Semiconductor strain gage
D. None of the mentioned

Answer: A

A semiconductor strain gauge is much more sensitive than a wire type and so, it provides better accuracy and resolution.


58. How a differential instrumentation amplifier using a transducer bridge can be used as a temperature controller?

A. Increase room temperature
B. Replaces calibrated meter with relay
C. Change the bridge resistance
D. Replace the thermistor with a light intensity meter

Answer: B

A simple and inexpensive temperature controller can be constructed by replacing a meter with a relay in the circuit. So, the output of the differential instrumentation amplifier drives a relay that controls the current on the heat-generating circuit.


59. The strain gage elements in the analog weight scale are mounted on a

A. Base of weight platform
B. Hanging weight platform
C. Loading weight platform
D. Varying weight platform

Answer: A

The strain gauge elements are mounted on the base of the weight platform. So, whenever the external force or weight is applied to the platform, one pair of elements in the opposite arm of the bridge elongates, whereas the other pair in the opposite arm compresses.


60. What will be the resultant circuit, when the thermistor in the bridge transducer is replaced by a strain gage?

A. Differential input and differential output amplifier
B. Light intensity
C. Analog weight scale
D. None of the mentioned

Answer: C

By connecting a strain gauge in the transducer bridge, the differential instrumentation amplifier circuit can be converted into a simple and inexpensive analog weight scale.

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