11. Strain gauge measurement involves __________
a) Wheatstone bridge
b) Kelvin bridge
c) De Sauty’s bridge
d) Anderson bridge
Answer: a
Explanation: Strain gauge makes use of the practical form of Wheatstone’s bridge to measure the strain developed by an element.

12. Load cell is used for the measurement of _______
a) area
b) force
c) mass
d) length
Answer: b
Explanation: The load cell is used in a semiconductor strain gauge for the measurement of force. Load cells measure the deformation that is produced by force or weight.

13. Strain is a _______
a) fractional change in volume
b) fractional change in area
c) fractional change in length
d) fractional change in height
Answer: c
Explanation: Strain is defined as the fractional change in length of a body. A change in resistance of the element is reflected in the form of strain of the gauge as well as the element.

14. Semiconductor strain gauge uses _______
a) rectifier circuitry
b) power electronics circuitry
c) ordinary bridge circuit
d) bridge circuit with temperature compensation
Answer: d
Explanation: The semiconductor strain gauge makes use of a Wheatstone practical bridge circuit along with temperature compensation. Output is made linear as the resistance characteristics with respect to strain are non-linear.

15. A semiconductor strain gauge consists of how many dummy gauges?
a) 2
b) 4
c) 6
d) 10
Answer: a
Explanation: The semiconductor strain gauge consists of two dummy gauges in the form of two arms of the Wheatstone bridge circuit. Dummy gauges are used for temperature compensation.

16. Metals in strain gauge construction have _______
a) non-linear temperature coefficient
b) linear temperature coefficient
c) tangential temperature coefficient
d) exponential temperature coefficient
Answer: b
Explanation: The metals used in a strain gauge construction have a linear temperature coefficient. A change in the temperature affects the resistance and varies the value of strain.

17. A Wheatstone bridge has _______
a) low sensitivity
b) zero sensitivity
c) high sensitivity
d) infinite sensitivity
Answer: c
Explanation: A Wheatstone bridge circuit has a high sensitivity for detecting very small variation in the values of resistance. We can connect the strain gauge in one of the arms of a Wheatstone bridge and measure the strain in terms of variation in resistance.

18. Load cells are calibrated such that _______
a) force varies inversely with resistance
b) force varies as the square of resistance
c) force remains constant with resistance
d) force varies directly with resistance
Answer: d
Explanation: The load cells in a semiconductor strain gauge are calibrated in such a way that the force or weight varies directly as the resistance. The strain gauge is arranged in the form of a bridge.

19. Load cell is sensitive to minute strains.
a) True
b) False
Answer: a
Explanation: A load cell responds to very minute variation in the value of strain. It is sensitive to high values of the load.

20. Mass of only about 20 kg can be measured by a load cell.
a) True
b) False
Answer: b
Explanation: Using a load cell a mass or weight of the order of 20 kg to 20,000 kg can be measured. By making use of appropriate load cells we can measure forces as high as 5 MN.

21. Electrical strain gauge works on the principle of __________
a) variation of resistance
b) variation of capacitance
c) variation of inductance
d) variation of area
Answer: a
Explanation: An electrical strain gauge works on the basis of change in resistance as a function of strain. The wire resistance increases with tension and reduces with compression.

22. The strain gauge is not bonded to the specimen.
a) True
b) False
Answer: b
Explanation: The gauge is under the same strain as that the specimen under test. As a result the strain gauge is bonded to the specimen.

23. Bonding element in a strain gauge must have __________
a) zero insulation resistance
b) low insulation resistance
c) high insulation resistance
d) infinite insulation resistance
Answer: c
Explanation: In a strain gauge, the bonding element must have a high value of insulation resistance. It should be immune to effects of moisture and must also have the ability to transmit strain.

24. Dynamic strain measurements use __________
a) brass iron alloy
b) iron aluminium alloy
c) nickel cadmium alloy
d) nickel chromium alloy
Answer: d
Explanation: Nickel chromium alloy is also known as a nichrome alloy. It contains 80 % of Nickel and 20 % of Chromium. Platinum is used for the temperature compensation of nickel chromium alloys.

25. Commonly used elements for wire strain gauges are __________
a) nickel and copper
b) nickel and gold
c) gold and brass
d) silver and aluminium
Answer: a
Explanation: Nickel and copper are the most commonly used elements for wire strain gauges. They comprise of 45 % of Nickel and 55 % of Copper. They exhibit a high value of specific resistance.

26. Cement is classified under __________
a) 4 types
b) 2 types
c) 6 types
d) 8 types
Answer: b
Explanation: Cement can be divided into two broad categories. They are as follows:
i) Solvent setting cement
ii) Chemically reacting cement.

27. Proper functioning of a strain gauge depends on __________
a) strain
b) stress
c) bonding
d) length of wire
Answer: c
Explanation: A strain gauge works properly only if the bonding material used is durable and keeps the gauge together to the surface of the material that is being tested.

28. Gauge factor is given by which of the following relation?
a) S = ΔR/RΔl
b) S = ΔRΔl/l
c) S = RΔl/l
d) S = ΔR/RΔl/l
Answer: d
Explanation: Gauge factor in a strain gauge is given by the relation
S = ΔR/RΔl/l
where, S is the gauge factor
R is the gauge wire resistance
∆R is the change in resistance
l is the length of the wire in unstressed condition
∆l is the change in length of the wire.

29. Poisson’s ratio is given by which of the following relation?
a) µ = –Δd/dΔl/l
b) µ = –ΔdΔl/l
c) µ = –dΔl/l
d) µ = –Δd/dΔl
Answer: a
Explanation: Poisson’s ratio is given by the relation
µ = –Δd/dΔl/l
where, d is the diameter of the cross-section of the wire
∆d is the change in the diameter of cross-section of the wire.

30. Proper bonding causes errors in strain gauges.
a) True
b) False
Answer: b
Explanation: Strain gauge is fixed onto the specimen by means of a bonding element. Cement is a commonly used adhesive. It transfers the strain from the specimen to the gauge sensing element.

31. What does the accelerometer measure?
a) Mass
b) Acceleration
c) Velocity
d) Distance
Answer: b
Explanation: The accelerometer is a type of inertial instrument that measures the acceleration in any given axes. The measured acceleration can be integrated over time to obtain velocity and distance.

32. What is the output given by an accelerometer if the instrument is accelerated upward with an acceleration of 7g?
a) 5g
b) 8g
c) 6g
d) 6.5g
Answer: b
Explanation: Accelerometer is used to measure acceleration of the vehicle and thus must be corrected for the Earth’s gravitational effect. If the accelerometer is being accelerated upward with an acceleration of 7g, then (a-G) = 7g – (-1g), and the instrument reads 8g.

33. Which accelerometer uses torquer coil and pick off supported by a flexure to measure acceleration?
a) MEMS accelerometer
b) Flexure pivot accelerometer
c) Vibrating beam accelerometer
d) Mechanical accelerometer
Answer: b
Explanation: The flexure pivot accelerometer is the most commonly used in aircraft systems. The sensitive element consists of a pendulum with a torquer coil and a pick off supported by torsional spring or flexure.

34. In flexure pivot accelerometer, the torque current is a measure of acceleration.
a) True
b) False
Answer: a
Explanation: The torquer coil in the accelerometer restore the pendulum to null, the torquer current being a measure of the restoring torque and, hence, of the acceleration.

35. Why do accelerometers that include fluid damping exhibit reduced damping?
a) State of fluid
b) Density
c) Pressure
d) Thermal characters
Answer: d
Explanation: Accelerometers that include fluid damping exhibit reduced bandwidth and additional thermal sensitivity due to changes in fluid characteristics. Thus flexure pivoted accelerometers are better than floated instruments.

36. An accelerometer can only measure acceleration in one direction?
a) True
b) False
Answer: a
Explanation: An accelerometer can only measure acceleration in one axes. In navigational systems comprising of accelerometers, three separate accelerometers are places with each on the three body axes of the aircraft.

37. Which of the following is true with respect to flexure pivot accelerometers?
a) Flexure must provide maximum resistance in the direction of input axis
b) Flexure must provide maximum resistance in the direction other than input axis
c) Torquer coil current measures the acceleration
d) Unbalanced accelerometer type
Answer: a
Explanation: The pivot or flexure supporting the pendulum must provide minimal restraint for the pendulum in the direction of the input axis while exhibiting high stiffness in the other two directions. The spring constant of the flexure or pivot generates a restoring force that reduces the gain of the electronic restoring loop.

38. Which of the following conditions cause rectification of vibration inputs?
a) Heating
b) Low voltage
c) High voltage
d) Low current
Answer: a
Explanation: Heating of torquer coil due to rebalance current can lead to rectification of vibration inputs and must often be compensated. A pulse rebalance torquer maintains constant heating.

39. What does silicon accelerometers use for proof mass sensing and for rebalancing?
a) Pivot
b) Flexure
c) Metalised wafers
d) Single crystal silicon frame
Answer: c
Explanation: The frame, proof mass and hinges are made with single crystal silicon. Metalised wafers are used to enclose this and also serve as electrodes for sensing proof mass and rebalancing.

40. Which type of rebalancing technique use voltage applied to pendulum and electrode for correction?
a) Charge forcing
b) Voltage forcing
c) Current forcing
d) Potential forcing
Answer: b
Explanation: In potential forcing, a potential is applied to the pendulum and to one or both the electrodes. The voltage establishes electric fields that induce the charge of the nonconducting pendulum. This causes a net force to act on the proof mass.

41. What will be the value measured by an accelerometer in free fall?
a) Zero
b) Infinite
c) Error
d) 9.81
Answer: a
Explanation: In a free fall the accelerometer will measure value=0. In a stationary state the accelerometer will measure the acceleration due to gravity as 9.81 m/s² but in a free fall the acceleration of the falling accelerometer is also 9.81 m/s² in the same direction, therefore the relative acceleration of the accelerometer becomes zero.

42. Which is the name of the accelerometer that is used to measure the gravity of the earth?
a) MPU6050
b) Gravitymeter
c) Gravitometer
d) Gravimeter
Answer: d
Explanation: Gravimeter are the accelerometer that is used to measure the gravity of the earth. The gravity of the earth varies from place to place depending upon the type of plain, plateau etc. This determination of acceleration due to gravity is called gravimetry.

43. What is the exact value of acceleration due to gravity taken in consideration?
a) 10 m/s²
b) 9.80665 m/s²
c) 9 m/s²
d) 0 m/s²
Answer: b
Explanation: The exact standard acceleration due to gravity is taken as 9.80665 m/s². For general calculations it is assumed to be 10 m/s². It the acceleration in which the earth pulls all the object present on the surface of earth. This acceleration varies at the poles of the earth.

44. Which element is mostly used in the capacitive accelerometers for sensing?
a) Germanium
b) Silicon
c) Lead
d) Carbon
Answer: b
Explanation: Silicon is mostly used in the capacitive accelerometers for sensing. It is relatively cheap and exhibits far better performance in the low frequency range. They can provide a higher stability and linearity when operated in servo mode.

45. MEMS stands for ________
a) Micro electric mechanical system
b) Micro electro mechanical system
c) Mini electro mechanical system
d) Mini electronic mechanical system
Answer: b
Explanation: MEMS stands for Micro electro mechanical system. Accelerometers, Gyroscopes and pressure sensors are MEMS sensors. It is a technology using which most of the accelerometers and other sensors are designed.

46. Accelerometers can be used for sensing mechanical vibrations.
a) True
b) False
Answer: a
Explanation: Accelerometers can be used for sensing mechanical vibrations. They can detect even very precise vibrations in the machine. Since the vibration is in single plane a two axis accelerometer is best suited for the measurement.

47. Acceleration is a ______ quantity.
a) scalar
b) vector
c) tensor
d) resistive
Answer: b
Explanation: Acceleration is a vector quantity. It is a vector quantity because it depends on both, magnitude of acceleration as well as the direction of acceleration. Had it been only dependent on magnitude, it would be a scalar quantity but it is not so.

48. MPU6050 in an example of which type of sensor?
a) Acceleration sensor
b) Proximity Sensor
c) Ultrasonic sensor
d) Laser sensor
Answer: a
Explanation: MPU6050 is an example of Acceleration sensor. It consists both 3 axis accelerometer and 3 axis gyroscope, which is capable of measuring very precise movements and accelerations.

49. Piezoelectric accelerometers converts ________ energy to ______energy.
a) mechanical, sound
b) mechanical, electrical
c) sound, electrical
d) sound, electrical
Answer: b
Explanation: Piezoelectric accelerometers converts mechanical energy to electrical energy. The word piezoelectric is derived from a Greek word “piezein” which means to press or squeeze. When any mechanical variable such as force or shock is applied on the input, then it produces subsequent electrical signals which is used to measure its magnitude.

50. Which is an example of accelerometer?
a) OptoNCDT ILR 1030
b) OptoNCDT 1420
c) ADXl 335
d) EddyNCDT 3301
Answer: c
Explanation: ADXl 335 is an example of accelerometer. OptoNCDTILR 1030 and OptoNCDT 1420 are laser sensor used for computing distance and objects placed at very high distances. EddyNCDT 3301 is a Eddy currents sensor.

21. In _____________ velocity of fluid is constant on every point at a specific time.
a) Steady flow
b) Rotational flow
c) Non steady flow
d) None of the mentioned
Answer: a
Explanation: In steady flow fluid, velocity of all points will be constant at a specific time.

22. If all particle of fluid has a path parallel to the wall, it is known as ____________
a) Stream line flow
b) Laminar flow
c) Viscous flow
d) All of the mentioned
Answer: d
Explanation: If all particles of fluid have a parallel path with wall, it is called laminar flow which is also known as viscous flow and stream line flow.

23. Which of the following represents Reynolds number for laminar flow?
a) Less than 2000
b) Greater than 4000
c) Infinite
d) None of the mentioned
Answer: a
Explanation: Reynolds number is an indication of the flow of fluid, For a Reynolds number less than 2000, fluid is said to be in laminar flow. For greater than 4000 fluid is said to be in a turbulent flow.

24. Bernoulli’s theorem is applicable for fluid path with moderate frictional force.
a) True
b) False
Answer: b
Explanation: Bernoulli’s theorem is applied to obtain the total energy of the fluid at each of the two points separated by a distance and in a tapered pipeline. It assumes a frictionless path and viscous forces are negligible.

25. _____________ measures velocity at a point of fluid in a stream.
a) Venturi meter
b) pH meter
c) Pitot-Static tubes
d) None of the mentioned
Answer: c
Explanation: Pitot-static tubes are the devices used for measuring the velocity of the fluid.

26. Which of the following represents obstruction type flow measuring systems?
a) Centrifugal force type
b) Rotating vane system
c) Flow nozzle device
d) None of the mentioned
Answer: c
Explanation: In such systems, flow rate is measured by making an obstruction in the path of flow.

27. Static vane system causes pressure loss in flow.
a) True
b) False
Answer: a
Explanation: Static vane makes an obstruction in the path of fluid flow, which causes considerable pressure loss.

28. Which of the following represents the correct relation between flow rate and area of pipe?
a) Direct proportionality
b) Inverse proportionality
c) Equal
d) None of the mentioned
Answer: a
Explanation: Flow rate and area of cross section of pipe are directly proportional. That is when the area of pipe is increased flow rate also increases.

29. Which of the following converts flow to rotational motion?
a) Rotatic vane system
b) Rotameter flow system
c) Both rotameter flow system and rotatic vane system
d) None of the mentioned
Answer: a
Explanation: Rotatic vane system is used for measurement of flow rate of fluid, in which flow is converted into rotational motion.

30. Centrifugal force elements are used for ___________
a) High flow rate
b) Low flow rate
c) All range of flow rate
d) None of the mentioned
Answer: a
Explanation: Centrifugal force element for measuring flow rate is only applicable for high flow rate, below which it doesn’t produce any recognizable change.

31. Which of the following is correct for tactile sensors?
a) Touch sensitive
b) Pressure sensitive
c) Input voltage sensitive
d) Humidity sensitive
Answer: a
Explanation: Tactile sensors are those which sensitive to touch.

32. Change in output of sensor with change in input is ____________
a) Threashold
b) Slew rate
c) Sensitivity
d) None of the mentioned
Answer: c
Explanation: Sensitivity of a sensor is the change in output for a change in input.

33. Which of the following can be cause for non-zero output when zero input?
a) Bias
b) Slew
c) Offset
d) Offset or bias
Answer: d
Explanation: For ideal condition, zero input produces zero output.

34. Sensitivity of a sensor can be depicted by _______________
a) Niquist plot
b) Pole- zero plot
c) Bode plot
d) None of the mentioned
Answer: c
Explanation: Bode plot can be used for describing the sensitivity of a sensor.

35. Which of the following error is caused by a reversal of measured property?
a) Hysterisis
b) Noise
c) Digitization error
d) Quantization error
Answer: a
Explanation: Digitization error is caused by a reversal of measured value.

36. Smallest change which a sensor can detect is ____________
a) Resolution
b) Accuracy
c) Precision
d) Scale
Answer: a
Explanation: Resolution is the smallest change a sensor can detect.

37. Thermocouple generate output voltage according to ____________
a) Circuit parameters
b) Humidity
c) Temperature
d) Voltage
Answer: c
Explanation: Thermocouple is a device which is capable of producing output voltage according to input temperature.

38. Sensor is a type of transducer.
a) True
b) False
Answer: a
Explanation: Sensor is a device which enables measurement of input value.

39. Which of the following is not an analog sensor?
a) Potentiometer
b) Force-sensing resistors
c) Accelerometers
d) None of the mentioned
Answer: d
Explanation: All of the mentioned devices are analog sensors.

40. Measured property have no relation with error.
a) True
b) False
Answer: a
Explanation: Error of a system is independent of the measured value.

41. What is the full form of FIR in terms of signal filtering?
a) Finite impulse response
b) Finite impulse reduction
c) Finite impulse recombination
d) Filthy impulse response
Answer: a
Explanation: FIR in terms of signal filtering stands for Finite impulse response. It is a digital filter. The Impulse response of this filter is of a certain finite duration. The response settles to zero after some time.

42. Which frequency is attenuated in a Low-Pass filter?
a) High frequency
b) Low frequency
c) Mid-Range frequency
d) No frequency
Answer: a
Explanation: In a Low pass filter, High frequency is attenuated. It passes the frequencies only of Low-range and the frequency of high range is attenuated. The range may differ from filter to filter used for this purpose.

43. Which filter contains entirely passive elements?
a) Electrical filter
b) Mechanical filter
c) Digital filter
d) Optical filter
Answer: a
Explanation: Electrical filter contains entirely passive elements. These passive elements include resistors, inductors and capacitors. Electric filters were originally made from a combination of these passive elements.

44. Which is a signal generator module?
a) OptoNCDT ILR 1030
b) OptoNCDT1420
c) AD9850
d) EddyNCDT 3301
Answer: c
Explanation: AD9850 is a signal generator module. It can generate Sine signal. OptoNCDT ILR 1030 and OptoNCDT1420 are laser sensor used for computing distance and objects placed at very high distances. EddyNCDT 3301 is an Eddy currents sensor.

45. A system is said to be causal if its output depends on the future inputs.
a) True
b) False
Answer: b
Explanation: A system is said to be causal if its output does not depends on the future inputs. It is said to be causal only if it depends on the present and past inputs. If a system depends on the future input then the system is said to be non causal.

46. Capacitor can be used for signal filtering.
a) True
b) False
Answer: a
Explanation: Capacitor can be used for signal filtering. Capacitor is a device which stores charge. It can be used as a filter because it does not allow Direct current (DC) to pass through it, it only allows alternating current to pass through it.

47. Which family of filter has maximum flat frequency response?
a) Chebyshev filter
b) Bessel filter
c) Elliptic filter
d) Butterworth filter
Answer: d
Explanation: Butterworth filters have maximum flat frequency response among all other types of filter. Bessel filters have maximum flat phase delay. For a specific order and ripple, Elliptic filter has the steepest cut-off curve. Chebyshev filters show most appropriate ideal response.

48. Which family of filters have maximum flat phase delay?
a) Chebyshev filter
b) Bessel filter
c) Elliptic filter
d) Butterworth filter
Answer: b
Explanation: Bessel filters have maximum flat phase delay. Butterworth filters have maximum flat frequency response among all other types of filter. For a specific order and ripple, Elliptic filter has the steepest cut-off curve. Chebyshev filters show most appropriate ideal response.

49. What is the full form of IIR in terms of signal filtering?
a) Infinite impulse response
b) Infinite impulse reduction
c) Infinite impulse recombination
d) Instant impulse response
Answer: a
Explanation: IIR in terms of signal filtering stands for Infinite impulse response. It is a discrete time filter also known as digital filter. It depends linearly with the number of input samples and a finite number of previous filter inputs.

50. A system is said to be non causal if its present output depends on the future inputs.
a) True
b) False
Answer: a
Explanation: A system is said to be non causal if its present output depends on the future inputs. In non-causal system the inputs are the future responses of the system. If a system depends on the present and past inputs then the system is said to be causal system.

51. Which signal is obtained after integrating the unit step signal?
a) Square signal
b) Unit Step Signal
c) Ramp Signal
d) Parabolic Signal
Answer: c
Explanation: Ramp Signal is obtained after integrating the unit step signal. Integration of a curve gives the total area under the curve. For a standard unit step signal the value of signal is 0, so integration value is also 0. At index 0, the value of unit step signal is 1 but area under it is 0. So the integrated signal remains 0. But slowly the area under unit step signal increases constantly, so when it is integrated, gives out ramp function or ramp signal with constant slope.

52. Which signal is obtained after integrating the ramp signal (for x>0 in X-Axis)?
a) Square signal
b) Unit Step Signal
c) Ramp Signal
d) Parabolic Signal
Answer: d
Explanation: Parabolic Signal is obtained after integrating the ramp signal. Integration of a curve gives the total area under the curve.
Let us consider a ramp signal, Y=x
So its integration is (x²)/2 which clearly a parabolic signal.

53. Which signal is obtained after differentiating the ramp signal?
a) Square signal
b) Unit Step Signal
c) Ramp Signal
d) Parabolic Signal
Answer: b
Explanation: Unit Step Signal is obtained after differentiating the ramp signal. Differentiation gives the rate of change of a signal. Since integration and differentiation are reverse function of each other so integrating a unit step function also gives ramp signal back.

54. Which signal is obtained after differentiating the unit step signal?
a) UnitImpulse signal
b) Unit Step Signal
c) Ramp Signal
d) Parabolic Signal
Answer: a
Explanation: UnitImpulse signal is obtained after differentiating the unit step signal. Differentiation gives the rate of change of a signal. Since the only change occurs at point 0 in unit step signal so the differentiation of unit step signal becomes unit impulse signal at point 0.

55. Derivative of a unit step signal is zero everywhere.
a) True
b) False
Answer: b
Explanation: Derivative of a unit step signal is not zero everywhere. It is 0 at all points except at X=0 in XY plane. Differentiation gives the rate of change of a signal. Since the only change occurs at point 0 in unit step signal so the differentiation of unit step signal becomes unit impulse signal.

56. What is the slew rate of an ideal operational amplifier?
a) 0
b) 1
c) 100
d) Infinite
Answer: d
Explanation: The slew rate of an ideal operational amplifier is infinite. Slew rate of an operational amplifier is defined as the rate of change of output voltage with respect to time (i.e) dv/dt. An ideal operational amplifier takes no time to change the output, therefore dt=0. So dv/dt becomes infinite and hence an ideal operational amplifier has infinite slew rate.

57. What is the open loop gain of an ideal operational amplifier?
a) 0
b) 1
c) Infinite
d) -1
Answer: c
Explanation: The open loop gain of an ideal operational amplifier is infinite. Open loop gain of an operational amplifier is defined as output voltage divide by input voltage (Vout/Vin). In ideal case the operational amplifier produces infinite output voltage when very low input voltage is applied.

58. What is the phase difference between input signal and output signal when input is provided to the inverting terminal of the operational amplifier?
a) 0 degree
b) 90 degree
c) 180 degree
d) 45 degree
Answer: c
Explanation: There 180 degree phase difference between input signal and output signal when input is provided to the inverting terminal of the operational amplifier. When input is provided to the negative terminal it adds 180 degree phase shift to the input signal and inverts the input signal, that is why the terminal is also called as inverting terminal.

59. What is the slew rate of an operational amplifier whose output voltage increases by 9 volt in 18 micro second?
a) 0.5 Volt/microsecond
b) 5 Volt/microsecond
c) 50 Volt/second
d) 2 Volt/microsecond
Answer: a
Explanation: Given:
Change in voltage(dv)=9 Volt
Change in time(dt)= 18 micro second
Slew rate=dv/dt=9V/18 microsecond=0.5 volt/microsecond

60. A practical operational amplifier has infinite bandwidth.
a) True
b) False
Answer: b
Explanation: A practical operational amplifier does not have infinite bandwidth. It is so because at higher frequency signals the efficiency of amplification starts to decrease. The practical operational amplifier cannot amplify signals with very high frequency. Ideal operational amplifiers have infinite bandwidth.

61.An ideal Operational amplifier should have Infinite output resistance and zero input resistance.
a) True
b) False
Answer: b
Explanation: An ideal Operational amplifier should have zero output resistance and infinite input resistance. Infinite input resistance allows any input signal to drive the operational amplifier and zero output resistance facilitates the operational amplifier to drive infinite number of loads.

62. CMRR stands for ____
a) Common mode rejection ratio
b) Common mains rejection ratio
c) Common mode reluctance ratio
d) Common mode rejection rate
Answer: a
Explanation: CMRR stands for Common mode rejection ratio. It is the ability of the Operational Amplifier to reject the common mode signals in the inverting and non-inverting terminals. It is the ratio of differential voltage gain to common mode voltage gain.

63. Which of the integrated circuit mentioned below is the name of an operational amplifier?
a) BC541
b) LM741H
c) TIP122
d) TIP135
Answer: b
Explanation: LM741H is most commonly used operational amplifier. It comes in 8-pin TO-99 package with an operating voltage of +15 volt to -15 volt. It provides high voltage gain with a bandwidth of 1.5MHz.

64. PSRR stands for ________
a) Power Supply Relaxation Ratio
b) Power Supply Rejection Rate
c) Power Supply Rejection Ratio
d) Power Supply Rejecting Ratio
Answer: c
Explanation: PSRR stands for Power Supply Rejection Ratio. It is defined as the ratio of change in the input supply voltage to the equivalent output voltage it generates. An ideal operational amplifier has infinite power supply rejection ratio.

65. What is the common mode rejection ratio of an operational amplifier which has common mode gain=0.5 and differential gain=1200?
a) 600
b) 1200
c) 2400
d) 1200 db
Answer: c
Explanation: Given:
Common mode gain=0.5
Differential gain=1200
Common mode rejection ratio(CMRR)=differential gain(Ad) / common mode gain(Ac)
Ad/Ac=2400.

65. What is the slew rate of an operational amplifier whose output voltage increases by 6 volt in 12 micro second?
a) 0.5 Volt/microsecond
b) 5 Volt/microsecond
c) 50 Volt/second
d) 2 Volt/microsecond
Answer: a
Explanation: Given:
Change in voltage(dv)=6 Volt
Change in time(dt)=12 micro second
Slew rate=dv/dt=6V/12 microsecond=0.5 volt/microsecond

66. What is the slew rate of an operational amplifier whose output voltage increases by 5 volt in 15 micro second?
a) 0.33 Volt/microsecond
b) 3 Volt/microsecond
c) 50 Volt/second
d) 2 Volt/microsecond
Answer: a
Explanation: Given:
Change in voltage(dv)=5 Volt
Change in time(dt)=15 micro second
Slew rate=dv/dt=5V/15 microsecond=0.33 volt/microsecond

67. What is the common mode rejection ratio of an operational amplifier which has common mode gain=0.2 and differential gain=1300?
a) 650
b) 6500
c) 2400
d) 1200 db
Answer: b
Explanation: Given:
Common mode gain=0.5
Differential gain=1200
Common mode rejection ratio(CMRR)=differential gain(Ad)/common mode gain(Ac)
Ad/Ac=6500.

68. What is the common mode rejection ratio of an operational amplifier which has common mode gain=0.6 and differential gain=1000?
a) 650
b) 6500
c) 1666.66
d) 1200 db
Answer: c
Explanation: Given:
Common mode gain=0.6
Differential gain=1000
Common mode rejection ratio(CMRR)=differential gain(Ad) / common mode gain(Ac)
Ad/Ac=1666.66.

68. Common mode rejection ratio is defined as (common mode gain)/(differential mode gain).
a) True
b) False
Answer: b
Explanation: Common mode rejection ratio is defined as (differential mode gain)/ (common mode gain). It is the ability of the Operational Amplifier to reject the common mode signals in the inverting and non-inverting terminals.

11. What is the algebraic sum of the reference input and feedback?
a) Error Signal
b) Error Detector
c) Controlled system
d) Controlled output
Answer: a
Explanation: In the block diagram of a basic control system we see that the reference input is passed through Error detector or Comparator. The signal which leaves the same is the algebraic sum of reference input and feedback as the feedback wire is connected to the detector, so we call it error signal.

12. Feedback control systems are referred to as closed loop systems.
a) True
b) False
Answer: a
Explanation: Feedback control systems are also referred to as closed loop systems. In a closed loop, the actuating error signals, which is the difference between the input signal and the feedback signal is fed to the controller so as to reduce the error and bring the output of the system to the desired value.

13. Which principle does the linear system follow?
a) Principle of energy conservation
b) Principle of mass conservation
c) Principle of electromagnetism
d) Principle of superposition
Answer: d
Explanation: A linear system is one who obeys the principle of superposition. The principle of superposition states that the response produced by simultaneous application of two different forcing functions is equal to the sum of individual responses.

14. ______ control systems have unpredictable & non-repeatable.
a) Static
b) Dynamic
c) Deterministic
d) Stochastic
Answer: d
Explanation: Stochastic control systems are those who have unpredictable and non-repeatable response due to involvement of random parameters. Static systems is the system whose current output depends only on current input, dynamic system is a time dependent system and deterministic system’s response is predictable and repeatable.

15. The pressure inside the furnace is measured by _______
a) Gauge
b) Thermometer
c) Manometer
d) Barometer
Answer: a
Explanation: The pressure inside the furnace is measured by pressure gauge. In case the pressure increases or decreases beyond the desired value, the controller and the actuator will cause a change in the position of the damper.

16. On what difference does the pneumatic system works?
a) Speed
b) Pressure
c) Area
d) Length
Answer: b
Explanation: A pneumatic system works due to pressure difference of air or any other gas. Air at a pressure, pi is injected through the input manifold. It also consists of mass, coefficient of viscous friction and spring constant and the pressure difference created due to that, gives rise to pneumatic system.

17. In a thermal system, the temperature of the medium is ______
a) increasing
b) decreasing
c) zero
d) uniform
Answer: d
Explanation: To analyze a thermal system and determine its transfer function the temperature of the medium should be uniform. If the temperature is varying or zero the analysis will not be proper and a legitimate transfer function will not be the result.

18. How many parameters does process control refer to?
a) 1
b) 3
c) 5
d) 7
Answer: c
Explanation: Process control refers to control of five parameters which are level, flow, pressure, temperature, acidity of the process variable. A particular parameter has only one desired value.

19. What is the effect of feedback in the overall gain of the system?
a) Increases
b) Decreases
c) Zero
d) No change
Answer: b
Explanation: The feedback reduces the overall gain of the system. As soon as we introduce feedback in the system to make the system stable, gain is reduced.

20. In a temperature control system, what conversion in signal takes place?
a) Digital to Analog
b) Analog to Digital
c) Error to Digital
d) Error to Analog
Answer: b
Explanation: In a temperature control system, analog to digital conversion of signals take place. Automatic systems don’t understand analog signals as they only take digital inputs in the form of 0 & 1 so we use a analog to digital converter which converts the signal.

21. Which of the following is not the feature of modern control system?
a) Quick response
b) Accuracy
c) Correct power level
d) No oscillation
Answer: d
Explanation: For a good control system the speed of response and stability must be high and for the slow and sluggish response is not used and undesirable.

22. The output of the feedback control system must be a function of:
a) Reference input
b) Reference output
c) Output and feedback signal
d) Input and feedback signal
Answer: d
Explanation: Feedback control system has the property of reducing the error and that is by differencing the output with the desired output and as the equation of the output of the system is C=GR/1+GH.

23. The principle of homogeneity and superposition are applied to:
a) Linear time invariant systems
b) Nonlinear time invariant systems
c) Linear time variant systems
d) Nonlinear time invariant systems
Answer: c
Explanation: Superposition theorem states that for two signals additivity and homogeneity property must be satisfied and that is applicable for the LTI systems.

24. In continuous data systems:
a) Data may be continuous function of time at all points in the system
b) Data is necessarily a continuous function of time at all points in the system
c) Data is continuous at the inputs and output parts of the system but not necessarily during intermediate processing of the data
d) Only the reference signal is continuous function of time
Answer: b
Explanation: Continuous signals are the signals having values for the continuous time and if impulse response decays to zero as time approaches infinity, the system is stable.

25. A linear system at rest is subject to an input signal r(t)=1-e^-t. The response of the system for t>0 is given by c(t)=1-e^-2t. The transfer function of the system is:
a) (s+2)/(s+1)
b) (s+1)/(s+2)
c) 2(s+1)/(s+2)
d) (s+1)/2(s+2)
Answer: c
Explanation: c(t)=1-e^-2t
R(s)=1/s-1/s+1
C(s)=1/s-1/s+2
Tf=2(s+1)/(s+2).

26. In regenerating the feedback, the transfer function is given by
a) C(s)/R(s)=G(s)/1+G(s)H(s)
b) C(s)/R(s)=G(s)H(s)/1-G(s)H(s)
c) C(s)/R(s)=G(s)/1+G(s)H(s)
d) C(s)/R(s)=G(s)/1-G(s)H(s)
Answer: d
Explanation: Regenerating feedback is positive feedback and it increases the infinitely and hence the speed of response of the system reduces.

27. A control system whose step response is -0.5(1+e^-2t) is cascaded to another control block whose impulse response is e^-t. What is the transfer function of the cascaded combination?
a) 1/(s+2)(s+1)
b) 1/(s+1)s
c) 1/(s+3)
d) 0.5/(s+1)(s+2)
Answer: a
Solution: Laplace transform is the transformation that transforms the time domain into frequency domain and of both the cascaded systems are 1/(s+1)(s+2).

28. A transfer function has two zeroes at infinity. Then the relation between the numerator(N) and the denominator degree(M) of the transfer function is:
a) N=M+2
b) N=M-2
c) N=M+1
d) N=M-1
Answer: b
Explanation: Zeroes at infinity implies two poles at origin hence the type of the system is two and degree of denominator is M=N+2.

29. When deriving the transfer function of a linear element
a) Both initial conditions and loading are taken into account
b) Initial conditions are taken into account but the element is assumed to be not loaded
c) Initial conditions are assumed to be zero but loading is taken into account
d) Initial conditions are assumed to be zero and the element is assumed to be not loaded
Answer: c
Explanation: When deriving the transfer function of a linear element only initial conditions are assumed to be zero, loading cannot be assumed to be zero.

30. If the initial conditions for a system are inherently zero, what does it physically mean?
a) The system is at rest but stores energy
b) The system is working but does not store energy
c) The system is at rest or no energy is stored in any of its part
d) The system is working with zero reference input
Answer: c
Explanation: A system with zero initial condition is said to be at rest since there is no stored energy.

31. Consider the block diagram shown below:

If the transfer function of the system is given by T(s)=G1G2+G2G3/1+X. Then X is:
a) G2G3G4
b) G2G4
c) G1G2G4
d) G3G4
Answer: b
Explanation: Use the technique of making two different block diagram by dividing two summers and use the approaches of shifting take off point and blocks.

32. For the block diagram given in the following figure, the expression of C/R is:

a) G1G2G3/1-G2G1
b) G1G2/1-G1G2G3
c) G1G2G3/1-G1G2G3
d) G1G2/G3(1-G1G2)
Answer: a
Explanation: Block diagram is being converted into signal flow graphs by considering each take off point as a node and each forward transfer function as forward gain.

33. The transfer function from D(s) to Y(s) is :

a) 2/3s+7
b) 2/3s+1
c) 6/3s+7
d) 2/3s+6
Answer: a
Explanation: Y(s)/D(s)=2/3s+1/1+3*(2/3s+1)=2/3s+7.

34. The closed loop gain of the system shown in the given figure is :
a) -9/5
b) -6/5
c) 6/5
d) 9/5
Answer: b
Explanation: C(s)/R(s)=-3/1+3/2=-6/5.

35. The advantage of block diagram representation is that it is possible to evaluate the contribution of each component to the overall performance of the system.
a) True
b) False
Answer: a
Explanation: The advantage of the block diagram is that it is possible to get the contribution of each block to the overall performance of the system.

36. The overall transfer function from block diagram reduction for cascaded blocks is :
a) Sum of individual gain
b) Product of individual gain
c) Difference of individual gain
d) Division of individual gain
Answer: b
Explanation: Gain of block get multiplied when they are cascaded where cascaded means that the blocks are in series combination with no summer in between.

37. The overall transfer function of two blocks in parallel are :
a) Sum of individual gain
b) Product of individual gain
c) Difference of individual gain
d) Division of individual gain
Answer: a
Explanation: The gains get added as the blocks are connected in parallel with the summer in between and they are connected with the same sign.

38. Transfer function of the system is defined as the ratio of Laplace output to Laplace input considering initial conditions________
a) 1
b) 2
c) 0
d) infinite
Answer: c
Explanation: By definition transfer function is the ratio of the laplace output to the input but the initial conditions mainly the stored energy is zero.

39. In the following block diagram, G1=10/s G2=10/s+1 H1=s+3, H2=1. The overall transfer function is given by :

a) 10/11s²+31s+10
b) 100/11s²+31s+100
c) 100/11s²+31s+10
d) 100/11s²+31s
Answer: b
Explanation: C/R=G2G1/1+G2H2+G1G2H2
C/R=100/11s²+31s+100.

40. Oscillations in output response is due to :
a) Positive feedback
b) Negative feedback
c) No feedback
d) None of the mentioned
Answer: a
Explanation: Oscillations are the unwanted sinuoidal signals with high gain in positive feedback and s the damping factor is absent in the positive feedback system entirely oscillations are present.

11 . A unit integrator is applied to a modified system along with a ramp input. The modified value of the steady state error is 0.25. What was the initial value?
a) 0.05
b) 0.1
c) 0.15
d) 0.2
Answer:D

12 – The initial response when output is not equal to input is ______
a) Error response
b) Transient response
c) Dynamic response
d) Static response

Answer:B

13 – The steady state error for a unit step input is ________
a) 1/kp
b) 1/(1-kp)
c) 1/2kp
d) 1/(1+kp)

Answer:D

14 – For a unity feedback system, the open loop transfer function is G(s) = K(s+2)/s2 (s2+7s+12). What is the type of system?
a) One
b) Two
c) Three
d) Four

Answer:b

15 – 8. The For a unity feedback system the open loop transfer function is G(s) = K(s+2)/s2 (s2+7s+12). What is the value of Ka?
a) 12/k
b) k/12
c) k/6
d) 6/k

Answer:c
Solution: As limit s tends to zero : s2G(s) = K(s+2)/ (s2+7s+12) = k/6. Ka is the acceleration error constant which is calculated by the above method.

16 – For a system whose transfer function is G(s) =10/s (1+s), what are the dynamic error coefficients k2 & k3 respectively as k1 is infinity?
a) 11, 10.1
b) 10.1, 11
c) 10, 11.1
d) 9, 10.1

Answer:c
Solution :We should compare it with E(s)/R(s) = 1/k1+1/k2s+1/k3s2. G(s) = 10/s(1+s) is compared with the above equation which is the parent equation for calculating dynamic error constants where k1 comes as infinity and K2, K3 takes the value of 10 & 11.1 respectively.

17 – The Laplace transform of a parabolic signal is _______
a) 1
b) A/s3
c) A/s2
d) A/s

Answer:a

18 – The ramp input is applied to a unity feedback system with type number 1 and zero frequency 20. What is the percentage of steady state error?
a) 1%
b) 2%
c) 5%
d) 9%

Answer:c

19 – The steady state error for a unity feedback system for the input r(t) to the system G(s) = K(s+2)/s(s3+7s2+12s) is 6R/K. The input r (t) is _______
a) Rt2/2
b) Rt3/2
c) Rt5/2
d) Rt7/2
Answer:a

20 – Transient response analysis is done for_________ systems.
a) Unstable
b) Stable
c) Conditionally stable
d) Marginally stable

Answer:b

21 – Standard test signals in control system are:
a) Impulse signal
b) Ramp signal
c) Unit step signal
d) All of the mentioned
Answer:d

22 – The nature of transient response is revealed by ______________
a) Sine wave
b) Cos wave
c) Tan wave
d) Test signals

Answer:d

11. Stability of a system implies that :
a) Small changes in the system input does not result in large change in system output
b) Small changes in the system parameters does not result in large change in system output
c) Small changes in the initial conditions does not result in large change in system output
d) All of the above mentioned
Answer: d
Explanation: Stability of the system implies that small changes in the system input, initial conditions, and system parameters does not result in large change in system output.

12. A linear time invariant system is stable if :
a) System in excited by the bounded input, the output is also bounded
b) In the absence of input output tends zero
c) Both a and b
d) System in excited by the bounded input, the output is not bounded
Answer: c
Explanation: A system is stable only if it is BIBO stable and asymptotic stable.

13. Asymptotic stability is concerned with:
a) A system under influence of input
b) A system not under influence of input
c) A system under influence of output
d) A system not under influence of output
Answer: b
Explanation: Asymptotic stability concerns a free system relative to its transient behavior.

14. Bounded input and Bounded output stability notion concerns with :
a) A system under influence of input
b) A system not under influence of input
c) A system under influence of output
d) A system not under influence of output
Answer: a
Explanation: BIBO stability concerns with the system that has input present.

15. If a system is given unbounded input then the system is:
a) Stable
b) Unstable
c) Not defined
d) Linear
Answer: c
Explanation: If the system is given with the unbounded input then nothing can be clarified for the stability of the system.

16. Linear mathematical model applies to :
a) Linear systems
b) Stable systems
c) Unstable systems
d) Non-linear systems
Answer: b
Explanation: As the output exceeds certain magnitude then the linear mathematical model no longer applies.

17. For non-linear systems stability cannot be determined due to:
a) Possible existence of multiple equilibrium states
b) No correspondence between bounded input and bounded output stability and asymptotic stability
c) Output may be bounded for the particular bounded input but may not be bounded for the bounded inputs
d) All of the mentioned
Answer: d
Explanation: For non-linear systems stability cannot be determined as asymptotic stability and BIBO stability concepts cannot be applied, existence of multiple states and unbounded output for many bounded inputs.

18. If the impulse response in absolutely integrable then the system is :
a) Absolutely stable
b) Unstable
c) Linear
d) Stable
Answer: a
Explanation: The impulse response must be absolutely integrable for the system to absolutely stable.

19. The roots of the transfer function do not have any effect on the stability of the system.
a) True
b) False
Answer: b
Explanation: The roots of transfer function also determine the stability of system as they may be real, complex and may have multiplicity of various order.

20. Roots with higher multiplicity on the imaginary axis makes the system :
a) Absolutely stable
b) Unstable
c) Linear
d) Stable
Answer: b
Explanation: Repetitive roots on the imaginary axis makes the system unstable.

21. Roots on the imaginary axis makes the system :
a) Stable
b) Unstable
c) Marginally stable
d) Linear
Answer: c
Explanation: Roots on the imaginary axis makes the system marginally stable.

22. If the roots of the have negative real parts then the response is ____________
a) Stable
b) Unstable
c) Marginally stable
d) Bounded
Answer: d
Explanation: If the roots of the have negative real parts then the response is bounded and eventually decreases to zero.

23. If root of the characteristic equation has positive real part the system is :
a) Stable
b) Unstable
c) Marginally stable
d) Linear
Answer: b
Explanation: The impulse response of the system is infinite when the roots of the characteristic equation has positive real part.

24. A linear system can be classified as :
a) Absolutely stable
b) Conditionally stable
c) Unstable
d) All of the mentioned
Answer: d
Explanation: A system can be stable, unstable and conditionally stable also.

25. ___________ is a quantitative measure of how fast the transients die out in the system.
a) Absolutely stable
b) Conditionally stable
c) Unstable
d) Relative Stability
Answer: d
Explanation: Relative Stability may be measured by relative settling times of each root or pair of roots.

26. Assertion (A): Relative stability of the system reduces due to the presence of transportation lag.
Reason (R): Transportation lag can be conveniently handled by Bode plot.
a) Both A and R are true but R is correct explanation of A
b) Both A and R are true but R is correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: b
Explanation: Transportation lag can be conveniently handled on Bode plot as well without the need to make any approximation.

27. Assertion (A): The phase angle plot in Bode diagram is not affected by the variation in the gain of the system.
Reason(R): The variation in the gain of the system has no effect on the phase margin of the system.
a) Both A and R are true but R is correct explanation of A
b) Both A and R are true but R is correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer: c
Explanation: The variation in the gain of the system has effect on the phase margin but phase plot is not affected.

28. A system has poles at 0.01 Hz, 1 Hz and 80Hz, zeroes at 5Hz, 100Hz and 200Hz. The approximate phase of the system response at 20 Hz is :
a) -90°
b) 0°
c) 90°
d) -180°
Answer: a
Explanation: Pole at 0.01 Hz gives -180° phase. Zero at 5Hz gives 90° phase therefore at 20Hz -90° phase shift is provided.

29. The constant M-circle represented by the equation x^{^}2+2.25x+y^{^}2=-1.25 has the value of M equal to:
a) 1
b) 2
c) 3
d) 4
Answer: c
Explanation: Comparing with the M circle equation we have the value of M =3.

30. What is the value of M for the constant M circle represented by the equation 8x²+18x+8y²+9=0?
a) 0.5
b) 2
c) 3
d) 8

31. The constant N loci represented by the equation x^{^}2+x+y^{^}2=0 is for the value of phase angle equal to:
a) -45°
b) 0°
c) 45°
d) 90°
Answer: d
Explanation: Centre = (-0.5, 0)
Centre of N circle is (-1/2, 1/2N)
N =tanα
α =90°.

32. All the constant N-circles in G planes cross the real axis at the fixed points. Which are these points?
a) -1 and origin
b) Origin and +1
c) -0.5 and 0.5
d) -1 and +1
Answer: a
Explanation: Centre of N circle is (-1/2, 1/2N)
N =tanα
Constant –N circles always pass through (-1, 0) and (0, 0).

33. Consider the following statements:
Nichol’s chart gives information about.
i. Closed loop frequency response.
ii. The value of the peak magnitude of the closed loop frequency response Mp.
iii. The frequency at which Mp occurs.
Which of the above statements are correct?
a) 2 and 3
b) 1 and 2
c) 1 and 3
d) 1,2 and 3
Answer: d
Explanation: Nichol’s chart gives information about closed loop frequency response, value of the peak magnitude of the closed loop frequency response Mp and the frequency at which Mp occurs.

34. Which one of the following statements is correct? Nichol’s chart is useful for the detailed study analysis of:
a) Closed loop frequency response
b) Open loop frequency response
c) Close loop and open loop frequency responses
d) None of the above
Answer: a
Explanation: Nichol’s chart is useful for the detailed study analysis of closed loop frequency response.

35. In a bode magnitude plot, which one of the following slopes would be exhibited at high frequencies by a 4th order all-pole system?
a) -80dB/decade
b) -40 dB/decade
c) 40 dB/decade
d) 80 dB/decade
Answer: a
Explanation: A 4th order all pole system means that the system must be having no zero or s-term in numerator and s⁴ terms in denominator. One pole exhibits -20dB/decade slope, so 4 pole exhibits a slope of -80 dB /decade.

36. Frequency range of bode magnitude and phases are decided by :
a) The lowest and higher important frequencies of dominant factors of the OLTF
b) The lowest and highest important frequencies of all the factors of the open loop transfer function
c) Resonant frequencies of the second factors
d) None of the above
Answer: d
Explanation: T. F. = Kp (1+Tds)
There is only one zero which will give slope of +20dB/decade.

37. OLTF contains one zero in right half of s-plane then
a) Open loop system is unstable
b) Close loop system is unstable
c) Close loop system is unstable for higher gain
d) Close loop system is stable
Answer: c
Explanation: OLTF contains one zero in right half of s-plane then Close loop system is unstable for higher gain.

38. The critical value of gain for a system is 40 and gain margin is 6dB. The system is operating at a gain of:
a) 20
b) 40
c) 80
d) 120
Answer: a
Explanation: Gm (dB) = 20log⁡GM
GM =2
As we know, GM =K (marginal)/K (desired)
K desired =40/2 =20.

39. Nichol’s chart is useful for the detailed study and analysis of:
a) Closed loop frequency response
b) Open loop frequency response
c) Close loop and open loop frequency responses
d) open loop and Close loop frequency responses
Answer: a
Explanation: Nichol’s chart is useful for the detailed study and analysis of closed loop frequency response.

40. The roots of the characteristic equation of the second order system in which real and imaginary part represents the :
a) Damped frequency and damping
b) Damping and damped frequency
c) Natural frequency and damping ratio
d) Damping ratio and natural frequency
Answer: b
Explanation: Real part represents the damping and imaginary part damped frequency.

41. Which among the following is a unique model of a system?
a) Transfer function
b) State variable
c) Block diagram
d) Signal flow graphs
Answer: a
Explanation: Transfer Function is defined as the ratio of the Laplace output to the Laplace input with the zero initial conditions and is a unique model of the system.

42. Which among the following is a disadvantage of modern control theory?
a) Implementation of optimal design
b) Transfer function can also be defined for different initial conditions
c) Analysis of all systems take place
d) Necessity of computational work
Answer: d
Explanation: Modern control theory is also not best suited in every respect it has also some disadvantages and the major disadvantage is that it requires computational work.

43. According to the property of state transition method, e0 is equal to _____
a) I
b) A
c) e^-At
d) -e^At
Answer: c
Explanation: By definition state transition matrix is defined as e^-At and this is the matrix that comes into the picture when the total response is considered that is with the free response and forced response.

44. Which mechanism in control engineering implies an ability to measure the state by taking measurements at output?
a) Controllability
b) Observability
c) Differentiability
d) Adaptability
Answer: b
Explanation: Observability and controllability are the two methods to check the output response characteristics and observability in control engineering implies an ability to measure the state by taking measurements at output.

45. State model representation is possible using _________
a) Physical variables
b) Phase variables
c) Canonical state variables
d) All of the mentioned
Answer: d
Explanation: State model representation is the representation of the control system is the form of the state variables and state vectors and is possible using physical variables, phase variables and canonical state variables.

46. Which among the following constitute the state model of a system in addition to state equations?
a) Input equations
b) Output equations
c) State trajectory
d) State vector
Answer: b
Explanation: Output Equations constitute the state model of a system in addition to state equations and for the complete state model mainly input model, output model and state models are required.

47. Which among the following plays a crucial role in determining the state of dynamic system?
a) State variables
b) State vector
c) State space
d) State scalar
Answer: a
Explanation: State Variables are the integral part of the state variable analysis and plays a crucial role in determining the state of dynamic system.

48. Which among the following are the interconnected units of state diagram representation?
a) Scalars
b) Adders
c) Integrator
d) All of the mentioned
Answer: d
Explanation: Scalars, adders and integrator are the interconnected units of state diagram representation and this representation helps in determination of the state of the control system.

49. State space analysis is applicable even if the initial conditions are _____
a) Zero
b) Non-zero
c) Equal
d) Not equal
Answer: b
Explanation: State space analysis is the analysis different from the transfer function approach as it has state variables and state vectors used for the analysis and can be used even if initial conditions are non-zero.

50. Conventional control theory is applicable to ______ systems
a) SISO
b) MIMO
c) Time varying
d) Non-linear
Answer: a
Explanation: The major advantage of state space analysis is that it can be applied to MIMO systems also while the conventional control theory that is transfer function approach is applicable to the SISO systems only.