# Control Systems Expected MCQ PDF 3 For Coal India Limited (CIL) MT Exam 2017

1)   Which system exhibits the initiation of corrective action only after the output gets affected?
a. Feed forward
b. Feedback
c. Both a and b
d. None of the above

2)   What should be the nature of bandwidth for a good control system?
a. Large
b. Small
c. Medium
d. All of the above

3)   If an impulse response of a system is e-5t, what would be its transfer function?
a. 1/ s – 5
b. 1/ s + 5
c. (s+1) / (s+5)
d. (s2 – 5s)/ (s-5)

4)   Which among the following are the elements of rotational motion?
a. Mass, Spring, Friction
b. Inertia, Damper, Spring
c. Work, Energy, Power
d. Force, Pressure, Viscocity

5)   Match the following notations with their meanings:
A. G(s) ———- 1) Laplace of error signal
B. H(s) ———- 2) Laplace of output signal
C. C(s) ———- 3) Forward transfer function
D. E(s) ———- 4) Feedback transfer function

a. A- 2, B- 3, C- 1, D- 4
b. A- 3, B- 4, C- 2, D- 1
c. A- 2, B- 3, C- 4, D- 1
d. A- 1, B- 2, C- 3, D- 4

 ANSWER: A- 3, B- 4, C- 2, D- 1
6)   At summing point, more than one signal can be added or _________
a. Subtracted
b. Multiplied
c. Both a and b
d. None of the above

7)   The value of variables at each node is _________the algebraic sum of all signals arriving at that node.
a. Less than
b. Equal to
c. Greater than
d. None of the above

8)   In signal
flow graph, the product of all ______gains while going through a forward
path is known as ‘Path gain’.

a. Branch
b. Path
c. Node
d. Loop

9)   If a type 1 system is subjected to parabolic input, what will be the value of steady state error?
a. 0
b. 100
c. Constant k
d. Infinite

10)   On which factor does the steady state error of the system depend?
a. Order
b. Type
c. Size
d. Prototype

11)   Consider the equation S3 + 3s2 + 5s + 2 = 0. How many roots are located in left half of s-plane?
a. Zero
b. Two
c. Three
d. Four

12)   If the system is represented by characteristic equation s6 + s4 + s3 + s2 + s + 3 = 0, then the system is_________
a. Stable
b. Unstable
c. Marginally stable
d. Unpredictable

13)   If poles are added to the system, where will the system tend to shift the root locus?
a. To the left of an imaginary axis
b. To the right of an imaginary axis
c. At the center
d. No shifting takes place

 ANSWER: To the right of an imaginary axis
14)   For a unity feedback system with G(s) = 10 / s2, what would be the value of centroid?
a. 0
b. 2
c. 5
d. 10

15)   If ‘ξ’ approaches to zero, the peak resonance would ________
a. Also be zero
b. Be unity
c. Tend to infinity
d. Become equal to peak overshoot

16)   At which
condition of ‘ξ’, resonant peak does not exist and its maximum value is
considered to be unity along with zero resonant frequency?

a. 0 < ξ < 0.707
b. ξ > 0.707
c. ξ = 0
d. ξ = 1

17)   If the
damping of the system becomes equal to zero, which condition of the
resonant frequency is likely to occur?

a. ωr = ωd
b. ωr > ωn
c. ωr < ωn
d. ωr = ωn

18)   If the
resonant peak is estimated to be ‘5’, which among the following would be
the correct value of damping?

a. ξ = 0.3
b. ξ = 1
c. ξ = 3.2
d. ξ = 5.55

19)   If a system is said to have a damping ξ = 0.5532 with the natural frequency ωn = 2 rad/sec, what will be the value of resonant frequency (ωr)?

20)   In frequency response, the resonance frequency is basically a measure of _______ of response.
a. Speed
b. Distance
c. Angle
d. Curvature

21)   The frequency at which the phase of the system acquires ____ is known as ‘Phase crossover frequency’.
a. 90°
b. -90°
c. 180°
d. -180°

22)   At which frequency does the magnitude of the system becomes zero dB?
a. Resonant frequency
b. Cut-off frequency
c. Gain crossover frequency
d. Phase crossover frequency

23)   If the phase
angle at gain crossover frequency is estimated to be -105°, what will
be the value of phase margin of the system?

a. 23°
b. 45°
c. 60°
d. 75°

24)   The system is said to be marginally stable, if gain margin is ______
a. 0
b. 1
c. +∞
d. None of the above

25)   If the constant ‘k’ is positive, then what would be its contribution on the phase plot?
a.
b. 45°
c. 90°
d. 180°

26)   If the unity feedback system is given by the open loop transfer function G(s) = ks2 / [(1 + 0.3s) (1+ 0.05s)], what would be the initial slope of magnitude plot?
d. Unpredictable

27)   If the
system is represented by G(s) H(s) = k (s+7) / s (s +3) (s + 2), what
would be its magnitude at ω = ∞?

a. 0
b.
c. 7/10
d. 21

28)   According to
Nyquist stability criterion, where should be the position of all zeros
of q(s) corresponding to s-plane?

a. On left half
b. At the center
c. On right half
d. Random

29)   Consider a
feedback system with gain margin of about 30. At what point does Nyquist
plot crosses negative real axis?

a. -3
b. -0.3
c. -30
d. -0.03

30)   For Nyquist contour, the size of radius is _______
a. 25
b. 0
c. 1
d.

31)   If a Nyquist
plot of G (jω) H (jω) for a closed loop system passes through (-2, j0)
point in GH plane, what would be the value of gain margin of the system
in dB?

a. 0 dB
b. 2.0201 dB
c. 4 dB
d. 6.0205 dB

32)   Which
principle specifies the relationship between enclosure of poles &
zeros by s-plane contour and the encirclement of origin by q(s) plane
contour?

a. Argument
b. Agreement
c. Assessment
d. Assortment

33)   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

34)   State model representation is possible using _________
a. Physical variables
b. Phase variables
c. Canonical state variables
d. All of the above

35)   Which
mechanism in control engineering implies an ability to measure the state
by taking measurements at output?

a. Controllability
b. Observability
c. Differentiability

36)   According to the property of state transition method, e0 is equal to _____
a. I
b. A
c. e-At
d. -eAt

37)   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