Free Control Systems MCQs with Answers
72 Control Systems MCQs from Electrical Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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- A. reduced velocity lag error
- B. increased velocity lag error
- C. increased speed of response
- D. reduced time constant of the system
Explanation: For a typical position servo, the velocity error is proportional to the friction coefficient and inversely related to loop gain, so…
Correct answer: reduced velocity lag error- A. Phase-lead
- B. Phase-lag
- C. Both A. and B.
- D. Either A. and B.
- E. None of the above
Explanation: A phase-lead compensator adds positive phase near the crossover frequency, increasing phase margin and effective damping.
Correct answer: Phase-lead- A. The range of air output as measured variable varies from maximum to minimum
- B. The range of measured variables from set value
- C. The range of measured variables through which the air output changes from maximum to minimum
- D. Any of the above
- E. None of the above
Explanation: Proportional band is the range of measured-variable values over which the controller output moves through its full range, usually from…
Correct answer: The range of measured variables through which the air output changes from maximum to minimum- A. Microsyn
- B. Selsyn
- C. Synchro-resolver
- D. Synchro-transformer
Explanation: A synchro-resolver converts angular information between coordinate systems, such as resolving shaft position into sine and cosine…
Correct answer: Synchro-resolver- 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 the above
Explanation: A lag-lead network contributes lag at low frequencies and lead at high frequencies, combining improved steady-state accuracy with improved…
Correct answer: lag at low frequencies and lead at high frequencies- A. reduces damping
- B. reduces the gain margin
- C. increases input noise
- D. increases error
Explanation: Differentiation magnifies high-frequency components, including unwanted measurement noise.
Correct answer: increases input noise- A. increases
- B. minimizes
- C. does not have any effect on
- D. any of the above
Explanation: Integral compensation accumulates the error over time and drives the steady-state error toward zero for suitable systems.
Correct answer: minimizes- A. The poles of the transfer function for a set of parameter values
- B. The bandwidth of the system
- C. The response of a system to a step input
- D. The frequency response of a system
- E. None of the above
Explanation: A root locus plots the locations of the closed-loop poles as a system parameter, usually the gain, varies.
Correct answer: The poles of the transfer function for a set of parameter values- A. Signal flow graph
- B. Analogous table
- C. Output-input ratio
- D. Standard block system
- E. None of the above
Explanation: A signal-flow graph represents the relationships among system variables, and Mason’s gain formula can be used to obtain the transfer…
Correct answer: Signal flow graph- A. Ramp input signal
- B. Sinusoidal input signal
- C. Unit impulse input signal
- D. Exponentially decaying signal
Explanation: A unit impulse excites all dynamic modes of a linear system and its response directly gives the system’s impulse response, from which the…
Correct answer: Unit impulse input signal- A. Manipulated variable
- B. Zero sequence
- C. Actuating signal
- D. Primary feedback
Explanation: The actuating, or error, signal is the algebraic difference between the reference input and the feedback signal, usually written as e(t) =…
Correct answer: Actuating signal- A. system stability
- B. sensitivity
- C. gain
- D. effects of disturbing signals
Explanation: Negative feedback generally improves stability by reducing the tendency of the system to oscillate or diverge.
Correct answer: system stability- A. The system is at rest and no energy is stored in any of its components
- B. The system is working with zero stored energy
- C. The system is working with zero reference signal
Explanation: Zero initial condition means the system starts from rest, so its energy-storing elements such as capacitors and inductors have no…
Correct answer: The system is at rest and no energy is stored in any of its components- A. Input
- B. Actuating
- C. Feedback
- D. Reference
Explanation: The actuating or error signal is the difference between the reference and feedback signals.
Correct answer: Actuating- A. Linear and time-in variant systems
- B. Linear and time-variant systems
- C. Linear systems
- D. Non-linear systems
- E. None of the above
Explanation: The conventional transfer function is defined using zero initial conditions for a linear time-invariant system, so it is independent of…
Correct answer: Linear and time-in variant systems- A. disturbance
- B. command
- C. control element
- D. reference input
Explanation: A disturbance is an unwanted input other than the reference command that changes the controlled variable.
Correct answer: disturbance- A. inertia forces
- B. internal forces
- C. stored energy
- D. friction
Explanation: Transient response results from the release, redistribution, or dissipation of energy initially stored in system elements such as…
Correct answer: stored energy- A. voltage
- B. current
- C. capacitance
- D. charge
- E. none of the above
Explanation: Temperature difference is the driving potential in a thermal system, just as voltage is the driving potential in an electrical circuit.
Correct answer: voltage- A. velocity
- B. pressure
- C. air flow
- D. air flow rate
Explanation: Air-flow rate represents the rate of movement of air, just as electric current represents the rate of movement of charge.
Correct answer: air flow rate- A. current
- B. charge
- C. inductance
- D. capacitance
Explanation: In the force-voltage analogy, force corresponds to voltage and velocity corresponds to current.
Correct answer: current