Control System Engineering Set 2

Electrical Engineering

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This set of Control System Engineering (CSE) Multiple Choice Questions & Answers (MCQs) focuses on Control System Engineering Set 2

Q1 | The principle of homogeneity and superposition are applied to:
  • linear time invariant systems
  • nonlinear time invariant systems
  • linear time variant systems
  • nonlinear time invariant systems
Answer: linear time variant systems
Explaination:
superposition theorem states that for two signals additivity and homogeneity property must be satisfied and that is applicable for the lti systems.
Q2 | In continuous data systems:
  • data may be continuous function of time at all points in the system
  • data is necessarily a continuous function of time at all points in the system
  • data is continuous at the inputs and output parts of the system but not necessarily during intermediate processing of the data
  • only the reference signal is continuous function of time
Answer: data is necessarily a continuous function of time at all points in the system
Explaination:
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.
Q3 | 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:
  • (s+2)/(s+1)
  • (s+1)/(s+2)
  • 2(s+1)/(s+2)
  • (s+1)/2(s+2)
Answer: 2(s+1)/(s+2)
Explaination:
c(t)=1-e-2t r(s)=1/s-1/s+1
Q4 | 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:
  • n=m+2
  • n=m-2
  • n=m+1
  • n=m-1
Answer: n=m-2
Explaination:
zeroes at infinity implies two poles at origin hence the type of the system is two and degree of denominator is m=n+2.
Q5 | When deriving the transfer function of a linear element
  • both initial conditions and loading are taken into account
  • initial conditions are taken into account but the element is assumed to be not loaded
  • initial conditions are assumed to be zero but loading is taken into account
  • initial conditions are assumed to be zero and the element is assumed to be not loaded
Answer: initial conditions are assumed to be zero but loading is taken into account
Explaination:
when deriving the transfer function of a linear element only initial conditions are assumed to be zero, loading cannot be assumed to be zero.
Q6 | If the initial conditions for a system are inherently zero, what does it physically mean?
  • the system is at rest but stores energy
  • the system is working but does not store energy
  • the system is at rest or no energy is stored in any of its part
  • the system is working with zero reference input
Answer: the system is at rest or no energy is stored in any of its part
Explaination:
a system with zero initial condition is said to be at rest since there is no stored energy.
Q7 | A signal flow graph is the graphical representation of the relationships between the variables of set linear algebraic equations.
  • true
  • false
Answer: true
Explaination:
by definition signal flow graphs are the graphical representation of the relationships between the variables of set linear algebraic equations.
Q8 | Use mason’s gain formula to find the transfer function of the given signal flow graph:
  • abd/1-(ac)
  • abdeg/1-(bc+ef)+bcef
  • abd/1-(bc+ef)+bcef
  • adcdef/1-(bc+ef)+bcef
Answer: abdeg/1-(bc+ef)+bcef
Explaination:
using mason’s gain formula transfer function from signal flow graph can be calculated which relates the forward path gain to the various paths and loops.
Q9 | Use mason’s gain formula to find the transfer function of the following signal flow graph:
  • abcd+efg/1-cd-fg-cdfg
  • acdfg+bcefg/1-cd-fg-cdfg
  • abef+bcd/1-cd-fg-cdfg
  • adcdefg/1-cd-fg-cdfg
Answer: acdfg+bcefg/1-cd-fg-cdfg
Explaination:
using mason’s gain formula transfer function from signal flow graph can be calculated which relates the forward path gain to the various paths and loops.
Q10 | Loop which do not possess any common node are said to be                        loops.
  • forward gain
  • touching loops
  • non touching loops
  • feedback gain
Answer: non touching loops
Explaination:
loop is the part of the network in which the branch starts from the node and comes back to the same node and non touching loop must not have any node in common.
Q11 | Signal flow graphs:
  • they apply to linear systems
  • the equation obtained may or may not be in the form of cause or effect
  • arrows are not important in the graph
  • they cannot be converted back to block diagram
Answer: they apply to linear systems
Explaination:
signal flow graphs are used to find the transfer function of control system by converting the block diagrams into signal flow graphs or directly but cannot be used for nonlinear systems.
Q12 | Signal flow graphs are reliable to find transfer function than block diagram reduction technique.
  • true
  • false
Answer: true
Explaination:
as one set technique and formula is used here but in block diagram technique various methods are involved which increases complexity.
Q13 | The relationship between an input and output variable of a signal flow graph is given by the net gain between the input and output node is known as the overall                             
  • overall gain of the system
  • stability
  • bandwidth
  • speed
Answer: overall gain of the system
Explaination:
the relationship between input and output variable of a signal flow graph is the overall gain of the system.
Q14 | Use mason’s gain formula to calculate the transfer function of given figure:
  • g1/1+g2h
  • g1+g2/1+g1h
  • g2/1+g1h
  • none of the mentioned
Answer: g1+g2/1+g1h
Explaination:
use mason’s gain formula to solve the signal flow graph and by using mason’s gain formula transfer function from signal flow graph can be calculated which relates the forward path gain to the various paths and loops.
Q15 | Use mason’s gain formula to find the transfer function of the given figure:
  • g1+g2
  • g1+g1/1-g1h+g2h
  • g1+g2/1+g1h+g2h
  • g1-g2
Answer: g1+g2/1+g1h+g2h
Explaination:
using mason’s gain formula transfer function from signal flow graph can be calculated which relates the forward path gain to the various paths and loops.
Q16 | Regenerative feedback implies feedback with
  • oscillations
  • step input
  • negative sign
  • positive sign
Answer: positive sign
Explaination:
regenerative feedback that is the positive feedback implies feedback with positive sign and for complementary root locus is for the regenerative feedback.
Q17 | The output of a feedback control system must be a function of
  • reference and output
  • reference and input
  • input and feedback signal
  • output and feedback signal
Answer: output and feedback signal
Explaination:
the response of the control system is the output of the control system that depends upon the transfer function of the system and feedback system and also upon the input of the system.
Q18 | A control system with excessive noise, is likely to suffer from
  • saturation in amplifying stages
  • loss of gain
  • vibrations
  • oscillations
Answer: saturation in amplifying stages
Explaination:
noise is defined as the unwnated output due to the input and this is
Q19 | Zero initial condition for a system means
  • input reference signal is zero
  • zero stored energy
  • initial movement of moving parts
  • system is at rest and no energy is stored in any of its components
Answer: system is at rest and no energy is stored in any of its components
Explaination:
zero initial condition means that the system is at rest and no energy is stored in any of its component.
Q20 | Transfer function of a system is used to calculate which of the following?
  • the order of the system
  • the time constant
  • the output for any given input
  • the steady state gain
Answer: the output for any given input
Explaination:
transfer function of a system is that ratio of laplace output to the laplace input at zero initial conditions and which is used to calculate the output for any given input.
Q21 | The band width, in a feedback amplifier.
  • remains unaffected
  • decreases by the same amount as the gain increase
  • increases by the same amount as the gain decrease
  • decreases by the same amount as the gain decrease
Answer: increases by the same amount as the gain decrease
Explaination:
the bandwidth is defined as the difference in the higher frequency to the input frequency and increase in the bandwidth leads to the noise and in a feedback amplifier increases by the same amount as the gain decreases.
Q22 | On which of the following factors does the sensitivity of a closed loop system to gain changes and load disturbances depend?
  • frequency
  • loop gain
  • forward gain
  • all of the mentioned
Answer: all of the mentioned
Explaination:
sensitivity is defined as the change in the output with respect to the change in the parameter variations and the change in the input and load disturbances depends upon frequency loop gain and forward gain.
Q23 | The transient response, with feedback system,
  • rises slowly
  • rises quickly
  • decays slowly
  • decays quickly
Answer: decays quickly
Explaination:
transient response is the response that is between time t=0 and at any time and behaviors depends upon the value of damping factor and maximum peak overshoot.
Q24 | The second derivative input signals modify which of the following?
  • the time constant of the system
  • damping of the system
  • the gain of the system
  • the time constant and suppress the oscillations
Answer: the time constant and suppress the oscillations
Explaination:
the time constant is the time required to attain the final value of the steady state and the value if less then the speed of response will be more and second derivative input signals modify suppress the oscillations.
Q25 | The transient response, yt(t), of a system becomes          as t tends to infinity.
  • 0
  • 1
  • infinity
  • undefined
Answer: 0
Explaination:
the transient response of a system slowly becomes 0 as the time, for which the input is given, increases. finally, the total response of the system is only the steady state response.
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