250+ Control System MCQ Test Questions

In this article, we shared the 250 plus control system MCQ questions and answers to test your knowledge.

Control System MCQ Test Questions

250+ Control System MCQ

The below list provides all the multiple-choice questions related to the control systems technical subject.

Answers are available at the bottom of the article.

1. The temperature, under thermal and electrical system analogy, is considered analogous to

C)none of these answers

2. As compared to electronic systems which of the following is not an advantage of pneumatic control system ?

A)More reliability
B)All of these answers
C)No fire hazards
D)Less manitenance requirement

3. Spring constant in force-voltage analogy is analogous to

C)reciprocal of capacitance

4. The input to a controller is always ____ signal.

A)an error
B)a sensed
C)a servo
D)any of these answers

5. Which of the following is the specification of optimal control problems ?

A)All of these answers
B)A starting time and state, end time and state
C)System must be represented by a state equation
D)A performance index to define the goal of the control system design
E)Boundary conditions

6. Which of the following statements is incorrect ?

A)If the output response to a bounded input signal result in constant amplitude or constant amplitude oscillation, then the system is limited stable
B)If a system response is stable for a limited range of variations of its parameters, it is called conditionally stable system
C)If a system output is an oscillatory signal for a sinusoidal signal, it is called relatively stable
D)If a system response is stable for all variation of its parameters, it is called absolutely stable system

7. ____ is a part of the human temperature control system.

A)Leg movement
C)Perspiration system
D)Digestive system

8. In a control system integral error compensation ____ steady state error

B)any of these answers
D)does not have any effect on

9. Which of the following happens as the type of a system increases ?

A)Steady state error for a particular function increases
B)Steady state error for a particular function decreases
C)Stability problem decreases
D)Any of these answers
E)None of these answers

10. In order to convert the angular position of a shaft into an electric signal, which of the following electromagnetic transducers can be used ?

A)Rotary LVDT
D)A.C. servometer

11. The output of a feedback control system must be a function of

A)reference and input
B)output and feedback signal
C)input and feedback signal
D)reference and output

12. Which of the following forces resists motion ?

A)Spring force
B)Inertia force
C)All of these answers
D)Damping force

13. In a stable control system saturation can cause which of the following ?

B)Low-level oscillations
C)High-level oscillations
D)Conditional stability

14. In electrical-pneumatic system analogy the current is considered analogous to

A)air flow rate
B)air flow

15. With feed back ____ reduces.

A)none of these answers
B)system stability
C)system stability and gain
D)system gain

16. In pneumatic systems the medium used is


17. Which of the following is an advantage of on line identification ?

A)For identification only the working input and output system signals are required for investigation
B)The transfer characteristics are found in the form of transfer functions only
C)Even in the presence of some nonlinearity the method will statistically linearize to give transfer characteristic at operating conditions
D)Identification is carried out in real time and it may be accomplished easily and quickly
E)All of these answers

18. In case of type-1 system steady state acceleration is


19. When synchro transmitter shaft is disconnected from the driving shaft it will run as

B)standstill component
D)burnout machine

20. By the use of which of the following the power amplification of a magnetic amplifier is increased ?

A)Negative feedback
B)Direct current in control winding
C)All of these answers
D)Resistive load circuit

21. Regenerative feedback implies feedback with

A)positive sign
B)step input
C)negative sign

22. The term confirmity is associated with which of the following ?

D)Magnetic amplifier

23. The value of a node in the signal flow graph is equal to the

A)none of these answers
B)difference of incoming and outgoing nodes
C)sum of all the incoming nodes
D)product of all the incoming nodes

24. Which of the following is an example of intentional non-linear systems ?

A)Contractor servos
B)All of these answers
C)Non-linear pitch or dampers in aircraft control
D)On-off transducers

25. The system response can be tested better with

A)ramp input signal
B)exponentially decaying signal
C)sinusoidal input signal
D)unit impulse input signal

26. As a result of introduction of negative feedback which of the following will not decrease ?

A)Band width
C)Overall gain

27. The phase lag produced by transportation relays

A)is inversely proportional to frequency
B)is independent of frequency
C)decreases linearly with frequency
D)increases linearly with frequency

28. The gain margin is the factor by which the gain of the system can be increased to make it


29. Steep out off characteristics will have

A)all of these answers
B)accurate cut-off
C)small peak response
D)low stability margin

30. By which of the following the order of the system can be determined ?

A)Number of poles at the origin
B)None of these answers
C)The number of stable roots of the system
D)any of these answers

31. Non-linearities can be

C)either incidental or intentional

32. Addition of zeros in transfer function causes which of the following ?

C)None of these answers
D)Lead-lag compensation

33. The root locus plot is symmetrical about the real axis because

A)all roots occur in pairs
B)complex roots occur is conjugate pairs
C)all of these answers
D)roots occur simultaneously in left hand and right hand plane

34. The feedback of the tachometer reduces the system’s

A)both time constant only and gain only
B)time constant only
C)none of these answers
D)gain only

35. Bi-metallic thermostat is a ____ controller.


36. Zero percent proportional band means

A)none of these answers
B)any of the answers
C)no change in control output
D)no change in measured variable
E)it is an on-off controller

37. The capacitance, in force-current analogy, is analogous to


38. ___ is not a form of non-linearity for a control system

B)All of these answers
D)Square-law transfer characteristics
E)None of these answers

39. In order to increase the clamping of a badly underdamped system which of the following compensators may be used?

B)Either Phase-lead and Phase-lag
C)Both Phase-lead and Phase-lag
D)None of these answers

40. Which of the following types of motor has printed windings?

A)Modular motor
B)None of these answers
C)Motor with disc shaped rotor
D)Motor with ferromagnetic rotor

41. Due to which of the following reasons excessive bond width in control systems should be avoided?

A)It leads to slow speed of response
B)It leads to low relative stability
C)Noise is proportional to band width
D)None of these answers

42. Which of the following is an open loop control system ?

A)Ward leonard control
C)Field controlled D.C. motor

43. If the bandwidth of a system is increased the response will

A)none of these answers
B)become factor
C)become slower
D)remain unaffected

44. Phase lag network does which of the following?

A)Decreases bandwidth
B)All of these answers
C)Maintains velocity gain constant
D)Increases system stability

45. In a control system, noise can be reduced by ____

A)none of these answers
B)reducing bandwidth and attenuating frequencies at which external signal gets coupled to the system
C)reducing bandwidth
D)increasing bandwidth

46. The maximum overshoot of a second order system can be increased by

A)any of these answers
B)decreasing damping frequency
C)increasing natural frequency
D)increasing damping factor

47. Any externally introduced signal affecting the controlled output is called a

D)gain control

48. In pneumetic systems a restriction volume combination is equivalent to

B)R.L. circuit
C)R.C. circuit
D)none of these answers
E)resonant circuit

49. If the complex poles of a system have greater real parts, their overshoot is

A)not effected
C)none of these answers

50. The steady-state output of a unity feedback control system is ____ reference input.

A)equal to
B)not related to
C)very near to
D)much more than

51. In hydraulic system power is transmitted by

A)fluid under pressure
D)none of these answers

52. Which of the following methods may be used to minimize the loading in potentiometers ?

A)Non-linearity may be introduced
B)Linearity may be introduced
C)Reference voltage may be increased
D)Length of wire may be increased

53. The lead compensator in a feedback system

A)speeds up the transient response
B)all of these answers
C)increases the system error constant to some extent
D)increases the margin of stability

54. A signal other than the reference input that tends to affect the value of the controlled variable is known as ____

B)control element
D)reference input

55. A.C. servomotor resembles ____

A)two-phase induction motor
B)Three-phase induction motor
C)universal motor.
D)direct current series motor

56. The first order control system, which is well designed, has a

A)small bandwidth
B)negative time constant
C)none of these answers
D)large negative transfer function pole

57. In closed loop control system, with positive value of feedback gain the overall gain of the system will

B)be unaffected
C)any of these answers

58. When the initial conditions of a system are specified to be zero it implies that the system is

A)at rest but stores energy
B)working normally with reference input
C)at rest without any energy stored in it
D)working normally with zero reference input

59. For open control system which of the following statements is incorrect?

A)Recalibration is not required for maintaining the required quality of the output
B)Errors are caused by disturbances
C)Construction is simple and maintenance easy
D)Less expensive

60. Velocity error constant of a system is measured when the input to the system is unit ____ function.


61. An amplidyne can give which of the following characteristics?

A)Constant current
B)Constant voltage
C)Constant current, constant voltage, and constant power
D)Constant current as well as constant voltage
E)None of these answers

62. By which of the following is the order of the system determined?

A)None of these answers
B)Number of stable roots of the system
C)Number of multiplying terms in the denominator
D)Number of poles at the original

63. ___ directly converts temperature into voltage.

B)None of these answers
E)Gear train

64. By which of the following methods viscous friction can be added to a servomechanism?

A)Increasing the temperature of the coil
B)Reducing shaft r.p.m.
C)Coupling a disc to the shaft which is immersed in a viscous medium
D)Increasing shaft r.p.m.

65. For which of the following reasons nonlinearities are introduced?

A)To achieve special characteristics
B)Both To simplify the system and To achieve special characteristics
C)To simplify the system
D)None of these answers

66. In case of an on-off controller the proportional band is

A)100 percent
B)none of these answers

67. A control system working under unknown random actions is called ____

A)adaptive control system
B)digital data system
C)stochastic control system
D)computer control system

68. Regenerative feedback implies feedback with

A)negative sign
B)positive sign
C)step input

69. In distributed systems the transportation delays are detrimental to stability due to which of the following reasons?

A)They produce transients
B)None of these answers
C)They produce both attenuation and phase lag
D)They produce a phase lag
E)They produce attenuation

70. Which of the following statements is incorrect?

A)The damping action of an electro hydro servo unit can be increased by closing the dashpot
B)A simple lever device can be used as a mechanical position control equipment
C)A synchro generator can be used as synchro motor and vice versa
D)Box car generator is used in sampled data system for clamping

71. In pneumatic instrumentation systems the pressure of compressed air used is around

A)5.5 bar
B)1.4 bar
C)1 bar
D)2.5 bar

72. By which of the following methods steady-state error can be minimized?

A)By increasing system gain constant
B)By decreasing natural frequency
C)By decreasing damped frequency
D)By increasing damped frequency

73. A stepper motor is a ____ device.

D)any of these answers

74. A zero-order hold is used with sampled data system to

A)improve the stability of the system
B)reconstruct the sampled signal
C)make it critically damped
D)convert it to a continuous system
E)none of these answers

75. Synchros’ are commonly used as transmitters of

A)angular data
B)none of these answers
C)digital data
D)computed data
E)graphical data

76. A signal flow graph is a

A)topological representation of a set of differential equations
B)log graph
C)special type of graph to analyse modern control systems
D)polar graph

77. Which of the following devices is used for conversion of coordinates?


78. A servo system will become absolutely unstable if

A)feedback path becomes zero
B)there is zero feedback
C)there is no feedback path
D)there is no stable component

79. For transistor amplifier circuits the common emitter configuration is used because it gives

A)high power gain
B)both high power gain and high voltage gain
C)none of these answers
D)high voltage gain

80. A gyroscope works on which of the following principles?

A)None of these answers
B)Law of conservation of momentum
C)First law of thermodynamics
D)Law of conservation of energy
E)Newton’s third law of motion

81. The proportional error device has output as a function of

A)integral of error
B)division of error
D)derivation of error
E)none of these answers

82. For a linear transfer function of the variable the transfer function of the system

A)does not change
C)has no relation at all
D)depends on other factors also

83. In an automatic control system which of the following elements is not used?

A)Final control element
B)Error detector

84. When the gain margin is positive and the phase margin is negative, the system is


85. When derivative action is included in a proportional controller, the proportional band ____

B)remains unaffected
C)none of these answers

86. As compared to a potentiometer which of the following is high for a LVDT?

A)None of these answers
B)Both Voltage sensitivity and Resolution
C)Voltage sensitivity

87. Which of the following can be measured by LVDT?

B)Any of these answers

88. In signal flow graph function points are called

C)none of these answers
D)functional points

89. ___ can be extended to systems which are time-varying ?

A)Bode-Nyquist stability methods
B)State model representatives
C)Root locus design
D)Transfer functions

90. The Bode plot is used to analyze which of the following?

A)All phase network
B)Maximum phase network
C)Lag lead network
D)Minimum phase network

91. The on-off controller is a ____ system.


92. For root loci which of the following are the starting points?

A)Open-loop zeros
B)Closed-loop zeros
C)Open-loop poles
D)Closed-loop poles

93. Which of the following is the non-linear system?

A)Servomotors working in saturation
B)Temperature controlled smelting furnace
C)Automatic voltage stabilizers
D)All of these answers

94. ____ signal will become zero when the feedback signal and reference signs are equal.


95. Backlash, in a stable control system, can cause which of the following?

C)All of these answers
D)Low-level oscillations

96. If a step function is applied to the input of a system and the output remains below a certain level for all the time, the system is

B)any of these answers
C)not necessarily stable
E)always unstable

97. Which of the following statements is incorrect for root locus technique?

A)It provides the pattern of movement of closed loop holes when open loop gain varies
B)It is used to obtain closed-loop pole configuration from open-loop poles and zeros
C)None of these answers
D)It is most useful for single-input single-output systems

98. In the case of a second order differential equation when the damping ratio is 1,

A)poles will be positive
B)poles will be complex conjugate
C)poles will be equal, negative and real
D)poles will be unequal

99. A conditionally stable system exhibits poor stability at

A)none of these answers
B)reduced values of open loop gain
C)low frequencies
D)increased values of open loop gain

100. Which of the following statements is incorrect?

A)For type-1 system, with unit ramp input, the steady state velocity constant is finite
B)For type-1 system the unit step input, the steady state error is zero
C)Derivative output compensation will increase settling time
D)The integral error compensation changes a second order system into a third order system

101. The type 2 system has which of the following ?

A)Constant position error as well as velocity error
B)Zero position error as well as velocity error
C)Constant position error and zero velocity error
D)Zero position error and constant velocity error

102. The transient response, with a feedback system

A)rises slowly
B)decays slowly
C)rises quickly
D)decays quickly

103. Which of the following devices is used to indicate angular position of an aircraft?

A)Rotating capacitor
B)Any of these answers
C)Rotatory differential transformer
D)Rotating transformer
E)None of these answers

104. By which of the following the control action is determined when a man walks along a path?


105. In a system of controlling oil flow to burner which of the following elements is not required?

A)Proportional controller
B)Turbine flowmeter
C)D.C. shunt motor

106. For a two-phase servomotor which of the following statements is incorrect?

A)Torque-speed characteristics are linear
B)The applied voltages are seldom balanced
C)The rotor diameter is small
D)The resistance of the rotor is low

107. The servomotor differs from other motors in the sense that it has

A)low inertia and low torque
B)entirely different construction
C)low inertia and high torque
D)high inertia and high torque

108. In open-loop system

A)the control action depends on the input signal
B)the control action is independent of the output
C)the control action depends on system variables
D)the control action depends on the size of the system

109. Type 1 system under parabolic input will have which of the following?

A)Parabolic output
B)Any of these answers
C)None of these answers
D)Actuating signal which will increase with time
E)Actuating signal which will decrease with time

110. The transfer function of a system can be used to evaluate

A)type of system
B)output for a given input
C)time constant
D)none of these answers

111. The type 1 system has ____ at the origin.

A)net pole
B)no pole
C)two poles
D)simple pole

112. In aircraft, the use of hydraulic motor is preferred over the electric motor because they are

A)not electrically driven
B)light and have high torque to inertia ratio

113. A transfer function may be best defined as

A)ratio of system response to the system input function
B)ratio of system input function to system response
C)Laplace transform of system response minus the Laplace transform of the system input function
D)none of these answers
E)ratio of the Laplace transform of the system response to the Laplace transform of the system input function

114. In a control application, the choice of error detector depends on

A)the accuracy desired
B)all of these answers
C)the nature of controlled variable
D)the type of control system

115. In a system low friction co-efficient facilitates

A)reduced time constant of the system
B)increased velocity lag error
C)increased speed of response
D)reduced velocity lag error

116. There is a ____ between the two nodes of the signal flow graph.

D)none of these answers

117. Selsyn’ is the trade name given to

A)spinning top
B)rotating capacitor
D)rotating transformer

118. A servomotor entails which of the following disadvantages?

A)Can handle only light loads
B)Low starting torque
C)Low reliability
D)Develops commutation problems

119. Static error coefficients are used as a measure of the effectiveness of closed-loop systems for specified ____ input signal.

A)all of these answers

120. In a non-linear control system limit cycle is self-sustained oscillations of

A)variable amplitude
B)fixed frequency and amplitude
C)variable frequency
D)fixed frequency

121. The gain of the amplidyne is related to the gain of D.C. generator of equivalent rating as ____ that of D.C. generator.

A)any of these answers
B)equal to
C)less than
D)more than

122. ___ is the input which is established or varied by some means external to and independent of the feed back control system

A)Modulated signal

123. The effect of error damping is to

A)provide larger settling lime
B)any of these answers
C)reduce steady state error
D)delay the response
E)none of these answers

124. For servomechanisms which of the following statements is incorrect?

A)a motor may be added to convert a regulator into a servo
B)some servo need not be stable since they are intended for use with steady signal
C)a servo with better frequency response need not be stable
D)steady-state accuracy of a servo is better than that of a regulator

125. Phase margin is the amount of angle to make the system


126. In pneumatic control systems compensation is provided by which of the following?

A)Flapper-nozzle mechanism
B)Restriction-volume combinations
C)Bimetal strips
D)Extension tubes

127. ___ has infinite resolution.

A)None of these answers
B)Deposited field potentiometer
C)Gall Tensley potentiometer
D)Kelvin’s double arm potentiometer

128. The frequency range specification required to satisfactorily describe the system response is

B)cut off range

129. Electrical capacitance in pneumatic systems is analogous to

A)restriction to flow
B)filled helical tube
C)none of these answers
D)volume of air

130. The operational amplifier used in servo amplification should have gain as

C)very high
D)very low

131. The transfer function of a system is used calculate which of the following ?

A)None of these answers
B)Type of the system
C)The output for a given input,
D)Time constant

132. Proportional band of a controller is expressed as

D)none of these answers
E)range of the control variable

133. Through which of the following the frequency domain analysis can be related to time doniain analysis ?

A)None of these answers
B)Laplace transformation
C)Both Laplace transformation and Fourier transformation
D)Fourier transformation

134. Zero initial condition for a system means ____

A)zero stored energy
B)input reference signal is zero
C)no initial movement of moving parts
D)system is at rest and no energy is stored in any of its components

135. Pressure error can be measured by which of the following ?

A)Strain gauge
B)Differential bellows and strain gauge
D)Strain gauge and potentiometer

136. LVDT is preferred over the potentiometer as an error detector because former

A)uses capacitance to minimize loading error
B)all of these answers
C)has high voltage sensitivity, low friction level and infinite resolution
D)produces a stronger actuating signal

137. In amplidyne the compensating winding is used to

A)increase the value of control voltage
B)compensate the effect of magnetic field set up by the load current
C)increase the control current
D)compensate for the power loss due to amplification

138. For a D.C. generator input could be in the form of

A)d.c. current
B)d.c. voltage induced
C)any of these answers
D)rotational speed

139. Microsy’ is a component based on the principle of

A)saturable reactor
C)none of these answers
D)d.c. motor
E)rotary differential transformer

140. The break away points of the root locus occur at

A)real axis
B)multiple roots of characteristic equation
C)none of these answers
D)imaginary axis

141. The phase difference between the two windings of A.C. servomotor is

B)none of these answers

142. Which of the following materials is used for making a stator of a synchro ?

A)Cast iron
B)Cadmium alloy
D)Laminated silicon steel
E)None of these answers

143. ____ is an open loop control system.

B)Ward Leonard control
C)Field controlled D.C. motor

144. Type 0 system has ____

A)both high gain constant and small steady state error
B)high gain constant
C)either high gain constant or small steady state error
D)small steady state error

145. Which of the following is the input to a controller ?

A)Error signal
B)Servo signal
C)Sensed signal
D)Desired variable value

146. In a pneumatic control valve the function of valve positioner is to eliminate

A)error in value-stem position
B)excessive hysteresis
C)the effects of air being compressible
D)all of these answers

147. The type 2 system has ____ at the origin.

A)net pole
B)simple pole
C)two poles
D)no net pole

148. Transfer function of a system is used to calculate which of the following ?

A)The steady state gain
B)The output for any given input
C)The time constant
D)The order of the system

149. In type-1 system a constant output velocity at steady state will be possible when there is

A)fluctuating error
B)constant steady state error
C)no error
D)variable steady state error

150. Mass, in force-voltage analogy, is analogous to


151. With feedback ____ increases.

A)effects of disturbing signals
B)system stability

152. ___ use hydraulic control devices ?

B)Machine tools
D)All of these answers

153. An automatic toaster is a ____ loop control system.

A)any of these answers
C)partially closed

154. A phase lag lead network introduces in the output

A)lag at all frequencies
B)lag at high frequencies and lead at low frequencies
C)lag at low frequencies and lead at high frequencies
D)none of these answers

155. In pneumatic-electrical analogy, the electrical resistance is analogous to

A)volume of air
B)restriction to flow
C)none of these answers
D)filled helical tube

156. The frequency range is specified by which of the following ?

A)Modulation index
B)Band width
D)Peak value

157. LVDT is an ____

A)electrostatic device
B)electromagnetic device
C)electro-mechanical device
D)electrodynamic device

158. In a control system noise can be avoided by which of the following methods ?

A)Reducing the bandwidth
B)Attenuating those frequencies at which external signals get coupled into the system
C)None of these answers
D)Both Reducing the bandwidth and Attenuating those frequencies at which external signals get coupled into the system

159. Which of the following statements is incorrect in respect of closed loop control system ?

A)Use of feedback minimizes the effects of disturbing signal
B)A D.C. closed loop control system has modulated wave forms
C)The source power of the feedback system is modulated by error signal
D)With feedback system the transient response decays more quickly

160. The operational amplifier is used for which of the following ?

A)Integration only
B)All common mathematical operations
C)Amplification only
D)Addition only

161. The magnitude of system output, for damping zero factor, will be

A)exponentially decaying

162. Which of the following is exhibited by Root locus diagrams ?

A)The response of a system to a step input
B)None of these answers
C)The frequency response of a system
D)The poles of the transfer function for a set of parameter values
E)The bandwidth of the system

163. In root locus plot different roots have the same

C)gain margin and phase margin
D)both phase and gain

164. An ideal transformer should have

A)a fine wire
B)an infinite resolution
C)zero resolution
D)resolution proportional to the reference voltage

165. In an open loop control system

A)Output is independent of control input
B)Output is dependent on control input
C)None of these answers
D)Only system parameters have effect on the control output

166. In thermal-electrical analogy charge is considered analogous to

A)reciprocal of heat flow
B)reciprocal of temperature
C)none of these answers
D)heat flow

167. If the clamping factor of a control system is unity it will give

A)critically damped response
B)undamped response
C)no response
D)oscillatoiy response

168. The effect of second derivative input control is to

A)none of these answers
B)control time constant of the system
C)both control time constant of the system and suppress oscillations
D)suppress oscillations

169. When damping factor decreases the per unit overshoot

A)remains unaffected
B)any of these answers

170. The root loci of a system has three asymptotes the system can have

A)five poles and two zeros
B)all of these answers
C)three poles
D)four poles and one zero

171. Which of the following is an electromechanical device ?

B)None of these answers
C)Induction relay
E)Any of the answers

172. Which of the following is the output of a synchor error detector ?

A)Suppressed-carrier modulated signal
B)Angular displacement of control transformer rotor
C)Voltage signal of the receiver
D)Voltage signal of constant amplitude

173. The input to a stepper motor is in the form of

A)electric pulses
B)frictional force
C)viscous damping force
D)mechanical interia

174. The value of the resonant peak, in second order control system, will be unity when the damping ratio has a value of

C)none of these answers

175. The time required for the response to reach half the final value for the first time is

A)decay time
B)pick-up time
C)delay time
D)rise time

176. In a magnetic amplifier the purpose of bias winding is

A)to produce initial saturation in core for high amplification
B)none of these answers
C)to weaken A.C. flux in the core
D)to weaken D.C. flux in the core

177. Gain margin is the factor by which the gain of the system is increased to make it


178. The position and velocity errors of a type-2 system are

A)zero, constant
B)constant, constant
C)zero, zero
D)constant, infinity

179. The type 0 system has ____ at the origin.

A)two poles
B)net pole
C)no pole
D)simple pole
E)none of these answers

180. Which of the following is the output of a thermocouple ?

A)Alternating current
B)Direct current
C)A.C. voltage
D)None of these answers
E)D.C. voltage

181. A servomechanism with unit step input can be categorised as ____ system

A)type 0
B)type 2
C)none of these answers
D)type 1
E)type 3

182. A pneumatic amplifier ____

A)amplifies flow
B)any of these answers
C)amplifies & differential pressure
D)amplifies change in air volume

183. ____ technique gives quick transient and stability response

B)Root locus

184. High power amplification is achieved by the use of

A)silicon controlled rectifier
B)A.C. amplifier
C)none of these answers
E)magnetic amplifier

185. Frequency domain analysis is preferred when dealing with systems having input as

A)ramp and parabolic
B)sinusoidal with variable frequency and amplitude
C)sinusoidal with fixed frequency
D)non-sinusoidal with lagging power factor

186. Synchros’ are popularly used as transmitter of

A)angular data
B)digital data
C)mathematical data
D)all of these answers

187. Nyquist criterion is used to find which of the following ?

A)Both Absolute stability and Relative stability
B)None of these answers
C)Absolute stability
D)Relative stability

188. A reduction gear is used to increase the

A)torque developed
B)viscous friction
C)moment of inertia
D)driven shaft speed

189. The initial response when the output is not equal to input is called

A)Dynamic response
B)Error response
C)Transient response
D)Either of these answers

190. The loading effect-on the potentiometer can be avoided by the use of

B)constant current source
C)none of these answers

191. A system which has some roots with real parts equal to zero but none with positive real parts is

A)relatively stable
B)absolutely unstable
C)marginally stable
D)absolutely stable

192. In order to decrease the time constant of the control system its ____ should be decreased.

A)steady state error
C)damping constant
D)viscous damping

193. A servomechanism is a feedback control system required to control

A)either position or some derivative of position
B)servoamplifiers and drives
D)some derivative of position

194. In a compressed air plant which of the following is not a function of the reservoir ?

A)Filtration of air
B)Cooling of air
C)Removal of pressure ripples
D)Storage of air

195. Which of the following is an advantage of Laplace transform method ?

A)None of these answers
B)Initial conditions are incorporated in the very first step
C)It gives solution in frequency domain only
D)Both It gives total solution more systematically and Initial conditions are incorporated in the very first step
E)It gives total solution more systematically

196. In pneumatic systems time lags are obtained by

A)any of these answers
B)making the air to fill a volume after passing through a restriction
C)elongating the path of air
D)pneumatic-electric elements

197. On which of the following factors does the resolution of a potentiometer depend ?

A)Shape of wire cross-section
B)Type of contact
C)Size of wire
D)Composition of wire material

198. A servomechanism with step displacement input will form ____ system.


199. Which of the following is an assumption made in Laplace technique in sampled data control ?

A)Sampler is ideal having make and break contacts operating instantly
B)Sampler is having sampled information fed to a linearily relaxed system
C)Sampler is working on periodic duty cycle
D)All of these answers
E)Sampler is having small pulse duration

200. ____ is preferred when a control signal is required to have a power level higher than the capability of linear electronic amplifiers.

B)A.C. servomotor
C)any of these answers
D)A.C. tachometer

201. ___ is not a final control element

A)Control valve
C)Electro-pneumatic convertor

202. Which of the following is the best method for determining the stability and transient response ?

A)Root locus
B)Nyquist plot
C)None of these answers
D)Bode plot

203. Hydraulic torque transmission system is analog of

A)resistance-capacitance parallel circuit
B)motor-generator set
C)amplidyne set
D)any of these answers

204. In a system the friction co-efficient is decreased to decrease

A)velocity lag error
B)system time constant
C)all of these answers
D)velocity lead

205. By which of the following the system response can be tested better ?

A)Exponentially decaying signal
B)Sinusoidal input signal
C)Unit impulse input signal
D)Ramp input signal

206. The effect of adding poles and zeros can be determined quickly by which of the following?

A)Bode plot
B)Nicholar chart
C)None of these answers
D)Nyquist plot
E)Root locus

207. The output of a stepper motor is in the form of

A)none of these answers
B)either linear movements or angular movements
C)angular movements
D)linear movements

208. Which of the following is the setting time in the second order linear system ?

A)4 times the time constant
B)1/4 of time constant
C)1/2 of time constant
D)2 times the time constant

209. A.C. servomotor, as compared to a standard induction motor has ____ inertia and ____ starting torque.

A)low, low
B)high, low
C)low, high
D)high, high

210. A system which has some roots with real parts equal to zero but none with positive real parts is

A)relatively stable
B)marginally stable
C)absolutely unstable
D)absolutely stable

211. The overshoot (an indication of the largest error between the actual and desired output) is the ratio of

A)none of these answers
B)dynamic error to peak error
C)maximum overshoot to final desired value
D)transient error to peak error

212. ___ is used for Nyquist plot.

A)Open loop function
B)Characteristic equation
C)Closed loop function
D)None of these answers

213. The transfer function technique is considered as inadequate under which of the following conditions ?

A)All of these answers
B)Systems having stability problems
C)Systems having complexities and non-linearities
D)Systems having multiple input disturbances

214. Regulator can be categorized as ____ system.


215. ___ is the serious disadvantage of electronic control systems.

A)Temperature sensitivenes
B)Low reliability
C)None of these answers
D)Operational difficulty

216. Which of the foaming is the main advantage of hydraulic system over electrical system ?

A)Easy balancing
B)No cooling problems
C)No danger of electric shock
D)Smaller size

217. By the used of which of the following high power amplification is achieved ?

A)D.C. amplifier
C)A.C. amplifier
D)Silicon controlled rectifier
E)None of these answers

218. In a system zero initial condition means that

A)The system is at rest and no energy is stored in any of its components
B)none of these answers
C)The system is working with zero reference signal
D)The system is working with zero stored energy

219. In a stable control system backlash can cause which of the following ?

A)Low-level oscillations
B)Poor stability at reduced values of open loop gain

220. An increase in gain, in most systems, leads to

A)none of these answers
B)constant damping ratio
C)larger damping ratio
D)smaller damping ratio

221. Which of the following statements is correct for any closed loop system ?

A)Only one of the static error co-efficients has a finite non-zero value
B)None of these answers
C)All the co-efficients can have zero value
D)All the co-efficients are always nonzero

222. Differential used in synchro differential unit indicates which of the following ?

A)Difference of rotation angle of two synchro generators
B)Rate of change of linear motion
C)Differential of analog signal to be transmitted
D)All of these answers

223. A car is running at a constant speed of 50 km/h, which of the following is the feedback element for the driver ?

A)Steering wheel
C)None of these answers
D)Needle of the speedometer

224. ____ will increase the steady state accuracy ?

B)Phase lag compensator
C)Phase lead compensator

225. The compressed air in pneumatic control systems is not

C)all of these answers

226. By which of the following methods the steady state error of a control system can be reduced ?

A)by increasing both time constant and gain constant
B)by increasing time constant of the system
C)none of these answers
D)by increasing gain constant of the system

227. A servomechanism usually consist of

A)error actuated signal
B)power amplifier
C)mechanical output
D)all of these answers

228. The steady state acceleration error for a type 1 system is

A)none of these answers
E)between zero and unity

229. By use of which of the following the system damping factor can be reduced ?

A)Positive feedback
B)Rate feedback
C)Negative feedback
D)Integral feedback

230. Sampled data systems final application in which of the following ?

A)All of these answers
B)High speed in plate rolling drives by using quantized data
C)Control mechanisms of automatic metal cutting lathes
D)Pulse controlled electric drives

231. In radars the control system used is

A)discrete data control system
B)none of these answers
C)continuous control system
D)relay control system

232. The viscous friction co-efficient, in force-voltage analogy, is analogous to

A)reciprocal of conductance
B)reciprocal of inductance
D)none of these answers

233. At which of the following root loci will end ?

A)Closed loop zeros
B)Closed loop poles
C)Open loop poles
D)Open loop zeros

234. A closed loop system is distinguished from open loop system by which of the following ?

B)Output pattern
C)Input pattern

235. Which of the following is an essential feature of servomechanism ?

A)A closed loop system
B)Ability to control position, velocity or acceleration of the system
C)A power amplifying stage
D)All of these answers

236. Which of the following statements is not nedessarily correct for open control system ?

A)Less expensive
B)Input command is the sole factor responsible for providing the control action
C)Presence of non-linearities causes mal-functioning
D)Generally free from problems of non-linearities

237. For root locus technique which of the following statements is incorrect?

A)It provides the pattern of movement of closed-loop poles when open loop gain varies
B)None of these answers
C)It is most useful for single-input single output systems
D)It is used to obtain closed loop pole configuration from open loop poles and zeros

238. The Bode plot is applicable to ____ network.

A)minimum phase
B)all phase
C)none of these answers
D)maximum phase

239. Which of the following is the definition of proportional band of a controller ?

A)None of these answers
B)The range of measured variables through which the air output changes from maximum to minimum
C)The range of air output as measured variable varies from maximum to minimum
D)The range of measured variables from set value
E)Any of the answers

240. System damping can be increased by using compensator having pair of complex roots as

A)phase lag
B)phase lead
C)phase lag lead
D)any of these answers

241. Which of the following statements is correct for a system with gain margin close to unity or a phase margin close to zero ?

A)The system is highly oscillatory
B)The system is highly stable
C)None of these answers
D)The system is relatively stable

242. A synchro is employed

A)to convert linear motion into angular motion
B)to accelerate a rotating shaft
C)to amplify low frequency signals
D)to convert an angular position of a shaft into an electrical signal

243. A controller essentially is a


244. Phase margin of a system is used to specify which of the following ?

A)Frequency response
B)Relative stability
C)Absolute stability
D)Time response

245. The transfer function is applicable to which of the following ?

A)Linear and time-in variant systems
B)Linear and time-variant systems
C)Non-linear systems
D)None of these answers

246. ___ cannot be the final control element.

B)Electro-pneumatic converter
C)All of these answers

247. Which of the following is the basic property of signal flaw graph ?

A)Signals travel along branches only in the marked direction and is multiplied by the gain of the branch
B)It is applicable to linear system only
C)All of these answers
D)The algebraic equations must be in the form of cause and effect relationship
E)Nodes are arranged from left to right in a sequence

248. In a hybrid feedback control system carrier signals are

A)only A.C.
B)both only A.C. and only D.C.
C)only D.C.
D)none of these answers

249. If the gain of the critical damped system is increased it will behave as

B)critically damped
C)none of these answers

250. Regenerative feedback means the output is feedback with

A)negative sign
C)positive sign

251. In pneumatic control systems the control valve used as final control element converts ____

A)none of these answers
B)pressure signal to position change
C)pressure signal to electric signal
D)position change to pressure signal
E)electric signal to pressure signal

252. ____ technique is not applicable to nonlinear system ?

A)Quasi linearization
B)Functional analysis
C)Nyquist Criterion
D)Phase-plane representation

253. The servomechanisms with step displacement input is

A)type 3 system
B)type 0 system
C)type 2 system
D)type 1 system

254. In pneumatic control system the output of a flapper-nozzle mechanism corresponds to

C)none of these answers
E)mechanical measurement

255. Which of the following is a disadvantage of a series D.C. motor ?

A)its speed regulation is poor
B)It requires high starting torque
C)It draws large currents
D)all of these answers

256. ___ is a closed loop system.

A)Electric switch
B)Direct current generator
C)Car starter
D)Auto-pilot for an aircraft

257. Bandwidth is used as a means of specifying performance of a control system related to

A)the speed of response
B)all of these answers
C)relative stability of the system
D)the constant gain

258. A limit switch is used to

A)limit the value of a signal
B)none of these answers
C)convert mechanical motion to electrical signal
D)convert electrical signal to mechanical signal
E)limit the motion of a drive

259. Because of which of the following the use of deposited film type potentiometer is limited.

A)Either Resistance varying with temperature or Infinite resolution
B)None of these answers
C)Resistance varying with temperature
D)Infinite resolution

260. The damping ratio of the system having only two poles, each having a negative real part, will be

A)infinitely high
C)any of these answerss

261. In a system nonlinearity may be introduced by which of the following ?

A)Saturation effects in amplifiers
B)Any of these answers
C)Backlash in gears
D)End positions in detectors

262. A control system with excessive noise, is likely to suffer from

B)loss of gain
C)saturation in amplifying stages

263. Which of the following should be done to make an unstable system stable ?

A)The gain of the system should be decreased
B)The number of zeros to the loop transfer function should be increased
C)The gain of the system should be increased
D)The number of poles to the loop transfer function should be increased

264. A minor loop feedback compensation increases the steady state error by a factor which is ____

B)inversely proportional to rate feedback
C)decaying exponentially
D)directly proportional to rate feedback

265. Which of the following devices are commonly used as error detectors in instruments ?

C)Any of these answers

266. The resolution of potentiometer should be

D)very high

267. A control system in which the control action is somehow dependent on the output is known as

A)Closed loop system
B)None of these answers
C)Open system
D)Semiclosed loop system

268. A good control system has all the following features except

A)sufficient power handling capacity
B)slow response
C)good accuracy
D)good stability

269. A differentiator is usually not a part of a control system because it ____

A)increases error
B)reduces the gain margin
C)increases input noise
D)reduces damping

270. Which of the following is the nonlinearity caused by servomotor ?

C)None of these answers
D)Static friction.

271. A.C. servomotor is basically a ____

A)single phase induction ‘actor
B)three phase induction motor
C)two phase induction motor
D)universal motor

272. ___ increases the steady state accuracy.

A)Phase lead compensator
C)Phase lag compensator

273. In system design which of the following is the disadvantage of differentiators ?

A)Large resistances and inductances in the circuit
B)Noise production and amplifier saturation
C)None of these answers
D)High cost

274. ___ system provides excellent transient as well as steady-state response

A)Proportional action
B)Proportional + integral action
C)Proportional + differential action
D)Proportional + integral + differential action
E)None of these answers

275. The transient response of a system is mainly due to

A)internal forces
B)inertia forces
C)stored energy

276. With the knowledge of state space representation the transfer function of the system

A)can be determined partly
B)none of these answers
C)cannot be determined
D)can be determined completely

277. Which of the following is incorrect ?

A)none of these answers
B)Nyquist criterion is in time domain
C)Routh’s criterion is in time domain
D)Bode plot is in frequency domain

278. ____ can measure pressure error.

C)Strain gauge
D)Any of these answers

279. The second derivative input signals modify which of the following ?

A)The gain of the system
B)None of these answers
C)Damping of the system
D)The time constant of the system
E)The time constant and suppress the oscillations

280. ___ is the reference input minus the primary feedback.

A)Zero sequence
B)Manipulated variable
C)Primary feedback
D)Actuating signal

281. Diodes are connected in series with A.C. source of the magnetic amplifier mainly to

A)act as filter
B)any of these answers
C)avoid desaturation of core due to negative half cycle
D)act as rectifier

282. A unit step function on integration results in a

A)unit ramp function
B)unit doublet
C)unit parabolic function
D)unit step function

283. The velocity lag error in the type-1 system is

A)inversely proportional to band width of the system
B)independent of gain constant
C)directly proportional to gain constant
D)inversely proprotional to gain constant

284. To maximize or minimize a set of criteria is called ____

A)optimal control policy
B)maximization control
C)limit differential function zero
D)minimization control

285. For system gain to be zero, the roots will move towards

D)none of these answers

286. The servosystem with step acceleration input is a ____ system.

A)type 1
B)type 2
C)type 0
D)type 3

287. In liquid level and electrical system analogy, voltage is considered analogous to

B)none of these answers
C)liquid flow
D)liquid flow rate

288. The overshoot is an indication of

A)largest error between the actual and desired output
B)least error between the actual and desired output
C)resonance between output and input
D)no error between the actual and desired output

289. On which of the following factors does the sensitivity of a closed loop system to gain changes and load disturbances depend ?

A)All of these answers
B)Loop gain
C)Forward gain

290. Which of the following can be measured by the use of a tacho generator?

B)Speed and acceleration
E)None of these answers

291. The effect of error rate damping is

A)to reduce steady state error
B)none of these answers
C)faster response
D)faster response and reduction in steady state error
E)faster response and larger settling time

292. For frequency domain analysis sinusoidal signals considered have ____ frequency.

A)any of these answers

293. ____ has tendency to oscillate.

A)Both Open loop system and Closed loop system
B)Closed loop system
C)Open loop system
D)Either Open loop system nor Closed loop system

294. A ‘drag cup’ type motor has which of the following ?

A)Low inertia
B)Low power rating
C)Low starting torque
D)None of these answers
E)Low damping

295. The eigen values of a linear system are the locations of

A)none of these answers
B)poles of the system
C)finite poles
D)zeros of the system

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