Explore topic-wise MCQs in Control System.

This section includes 180 Mcqs, each offering curated multiple-choice questions to sharpen your Control System knowledge and support exam preparation. Choose a topic below to get started.

51.

The open-loop transfer function of a unity feedback control system isG(s) H(s) = 30s(s + 1)(s + T)where T is a variable parameter. The closed-loop system will be stable for all values of

A. T > 0
B. 0 < T < 3
C. T > 5
D. 3 < T < 4
Answer» D. 3 < T < 4
Discussion
52.

The characteristic equation of a feedback control system is given by s3 + 5s2 + (K + 6) s + K = 0 where K > 0 is a scaler variable parameter. In the root-loci diagram of the system, the asymptotes of the root-locus for large values of K meet at a point in the s-plane, whose coordinates are

A. ( 3, 0)
B. ( 2, 0)
C. ( 1, 0)
D. (2, 0)
Answer» C. ( 1, 0)
Discussion
53.

Consider the following polynomials : 1. s4 + 7s3 + 17s2 + 17s + 6. 2. s4 + 11s3 + 41s2 + 61s + 30. 3. s4 + s3 + 2s2 + 3s + 2. Among these polynomials, those which are Hurwitz are

A. 1 and 3
B. 2 and 3
C. 1 and 2
D. 1, 2 and 3
Answer» D. 1, 2 and 3
Discussion
54.

The feedback system with characteristic equation s4 + 20 Ks3 + 5s2 + 10s + 15 = 0 is

A. stable for all value of K
B. stable for positive value of K
C. stable for > K > 7.0
D. unstable for all values of K
Answer» E.
Discussion
55.

The number of roots of the equation 2s4 + s3 + 3s2 + 5s + 7 = 0 that lie in the right half of s plane is

A. zero
B. one
C. two
D. three
Answer» D. three
Discussion
56.

The number of roots of s3 + 5 s2 + 7s + 3 = 0 in the right half of the s-plane is

A. zero
B. one
C. two
D. three
Answer» B. one
Discussion
57.

The phase margin of a system with the open-loop transfer functionG(s) H(s) = (1 - s) is(1 + s)(2 + s)

A. 0
B. 63.4
C. 90
D.
Answer» E.
Discussion
58.

A linear discrete-time system has t he characteristic equation, z3 0.81z = 0 The system

A. is stable
B. is marginally stable
C. is unstable
D. stability cannot be assessed from the given information
Answer» B. is marginally stable
Discussion
59.

In the root-locus for open-loop transfer functionG(s) H(s) = K(s + 6)(s + 3)(s + 5)The break away and break-in , points are located respectively at

A. 2 and 1
B. 2.47 and 3.77
C. 4.27 and 7.23
D. 7.73 and 4.27
Answer» E.
Discussion
60.

The open-loop transfer function of a unity feedback control system isG(s) = 1(s + 2)2The closed loop transfer function will have poles at

A. 2, 2
B. 2, 1
C. 2, j
D. 2, 2
Answer» D. 2, 2
Discussion
61.

The open-loop transfer function of a feedback control system is given byG(s) H(s) = K(s + 2)s(s + 4)(s2 + 4s + 8)I n the r oot locus diagram of the system, the asymptotes of the root loci for large values of K meet a point in the s-plane. Which one of the following is the set of co-ordinate of that point?

A. ( 1, 0)
B. ( 2, 0)
C. (2, 0)
Answer» C. (2, 0)
Discussion
62.

An open loop transfer function is given by, G(s) H(s) = K(s + 1)s(s + 2)(s2 + 25 + 2)It has

A. one zero at infinity
B. two zeros at infinity
C. three zeros at infinity
D. four zeros at infinity
Answer» D. four zeros at infinity
Discussion
63.

If open-loop transfer function of the system isG(s) H(s) = K(s + 10)s(s + 8)(s + 16)(s + 72)then a closed loop pole will be located at s = 12, when the value of K is

A. 4355
B. 5760
C. 9600
D. 9862
Answer» C. 9600
Discussion
64.

Which of the following points is NOT on the root locus of a system with the open-loop transfer functionG(s) H(s) = Ks(s + 1)(s + 3)

A. s = j
B.
C. s = 1.5
D. s = 3
E. s =
Answer» C. s = 1.5
Discussion
65.

The open loop transfer function of a unity feedback control system is given byG(s) = K(s + 2)s(s2 + 2s + 2)The centroid and angles of root locus asymptotes are respectively

A. zero and + 90 , 90
B. zero and + 120 , 120
Answer» B. zero and + 120 , 120
Discussion
66.

If characteristic equation of a closed-loop system is1 + K = 0s(s + 1)(s + 2)then centroid at the asymptotes in root-locus will be

A. zero
B. 2
C. 1
D. 2
Answer» D. 2
Discussion
67.

Consider a feedback control system with loop transfer functionG(s) H(s) = K(1 + 0.5s) s(1 + s)(1 + 2s)The type of the closed loop system is

A. zero
B. one
C. two
D. three
Answer» C. two
Discussion
68.

The root locus plot of the system having the loop transfer function,G(s) H(s) = K has s(s + 4)(s2 + 4s + 5)

A. no breakaway point
B. three real breakaway point
C. only one breakaway point
D. one real and two complex breakaway point
Answer» C. only one breakaway point
Discussion
69.

The root locus for K &lt; 0 for the transfer function expressed by G(s) H(s) = K s(s + 1)(s + 3)(s + 4)roughly drawn as

A. none of these
Answer» C.
Discussion
70.

The characteristic equation of a closed-loop system is given by s4 + 6s3 + 11s2 + 6s + K = 0 Stable closed loop behaviour can be ensured when gain K is such that

A. 0 < K < 10
B. K > 10
C. < K <
D. 0 < K < 20
Answer» B. K > 10
Discussion
71.

An electromechanical closed-loop control system has the following characteristic equation : s3 + 6 Ks2 + (K + 2) s + 8 = 0 where K is the forward gain of the system. The condition for closed loop stability is

A. K = 0.528
B. K = 2
C. K = 0
D. K = 2.58
Answer» B. K = 2
Discussion
72.

What is the unit step response of a unity feedback control system having forward path transfer function G(s) = 80s(s + 18)

A. Overdamped
B. Critically damped
C. Underdamped
D. Undamped oscillatory
Answer» E.
Discussion
73.

The performance specifications for a unity feedback control system having an open-loop transfer functionG(s) = Ks(s + 1)(s + 2)are (i) Velocity error coefficient Kv > 10 sec 1 (ii) Stable closed-loop operation. The value of K, satisfying the above specifications, is

A. K > 6
B. 6 < K < 10
C. K > 10
D. none of these
Answer» E.
Discussion
74.

If the unit step response of a network is (1 e t), then its unit impulse response will be

A. e
B. e
C. (1 - ) e
Answer» B. e
Discussion
75.

The bandwidth of a control system is the range of frequency over which | C/R (j )| is greater than or equal to

A. <table><tr><td rowspan="2"> </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> and it depends only on the undamped natural frequency of the system </td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">2</span></td></tr></table>
B. 1 and it depends only on the damping factor of the system
C. 1 and it depends only on the undamped natural frequency of the system
D. <table><tr><td rowspan="2"> </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> and it depends on both undamped natural frequency and the damping factor of the system</td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">2</span></td></tr></table>
Answer» C. 1 and it depends only on the undamped natural frequency of the system
Discussion
76.

A linear second-order single-input continuous-time system is described by the following set of differential equations :

A. controllable and stable
B. controllable but unstable
C. uncontrollable and unstable
D. uncontrollable but stable
Answer» C. uncontrollable and unstable
Discussion
77.

A linear time-invariant system describd by the state variable model

A. is completely controllable
B. is not completely controllable
C. is completely observable
D. is not completely observable
E. Both B and C options
Answer» F.
Discussion
78.

The maximum phase shift that can be provided by a lead compensator with transfer function

A. 15
B. 30
C. 45
D. 60
Answer» C. 45
Discussion
79.

Consider the system described by following state space equations

A. 0
B. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">2</td></tr></table>
C. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">3</td></tr></table>
D. 1
Answer» B. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">2</td></tr></table>
Discussion
80.

The Bode magnitude plot of H(j ) = 104 (1 + j ) is (10 + j )(100 + j )2

A. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-101.jpg">
B. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-102.jpg">
C. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-103.jpg">
D. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-104.jpg">
Answer» B. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-102.jpg">
Discussion
81.

A system with the open loop transfer function G(s) = K s(s + 2)(s2 + 2s + 2)

A. 2
B. 3
C. 4
D. 5
Answer» E.
Discussion
82.

The closed-loop transfer function of a system is T(s) = 4 (s2 + 0.4s + 4)

A. 0 to 0
B. 4 to 3
C. 1 to 5
D. None of the above
Answer» B. 4 to 3
Discussion
83.

An open loop control system results in a response of e

A. 241
B. 0.241
C. 41
D. 0.21
Answer» C. 41
Discussion
84.

The frequency response of a linear system G(j ) is provided in the tabular form below

A. 6 dB and 30
B. 6 dB and 30
C. 6 dB and 30
D. 6 dB and 30
Answer» B. 6 dB and 30
Discussion
85.

Which one of the following statements is NOT TRUE for a continuous time causal and stable LTI system ?

A. All the poles of the system must lie on the left side of the j axis.
B. Zeros of the system can lie anywhere in the splane.
C. All the poles must lie within | s | = 1.
D. All the roots of the characteristic equation must be located on the left side of the j axis.
Answer» D. All the roots of the characteristic equation must be located on the left side of the j axis.
Discussion
86.

A system with transfer function G(s) = (s2 + 9)(s + 2) is excited by sin ( t). (s + 1)(s + 3)(s + 4)

A. = 1 rad/s
B. = 2 rad/s
C. = 3 rad/s
D. = 4 rad/s
Answer» D. = 4 rad/s
Discussion
87.

The impulse response of a continuous time system is given by h(t) = (t 1) + (t 3). The value of the step response at t = 2 is

A. 0
B. 1
C. 2
D. 3
Answer» C. 2
Discussion
88.

A source v

A. 3
B. 4
C.
D. 5
E. 7
Answer» D. 5
Discussion
89.

The unilateral Laplace transform of f(t) is 1 . The unilateral Laplaces2 + s + 1

A. <table><tr><td rowspan="2">-</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>s</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">(s<sup>2</sup> + s + 1)<sup>2</sup></td></tr></table>
B. <table><tr><td rowspan="2">-</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2s + 1</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">(s<sup>2</sup> + s + 1)<sup>2</sup></td></tr></table>
C. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>s</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">(s<sup>2</sup> + s + 1)<sup>2</sup></td></tr></table>
D. <table><tr><td rowspan="2"></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2s + 1</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">(s<sup>2</sup> + s + 1)<sup>2</sup></td></tr></table>
Answer» E.
Discussion
90.

The frequency response of G(s) = 1 plotted in the complex G(j ) [s(s + 1)(s + 2)]

A. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-57.jpg">
B. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-58.jpg">
C. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-59.jpg">
D. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-60.jpg">
Answer» B. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-58.jpg">
Discussion
91.

The characteristic equation of a closed-loop system is s(s + 1)(s + 3) + k(s + 2) = 0, k > 0. Which of the following statements is true?

A. Its roots are always real
B. It cannot have a breakaway point in the range 1 < Re[s] < 0
C. Two of its roots tend to infinity along the asymptotes Re[s] = 1
D. It may have complex roots in the right half plane
Answer» D. It may have complex roots in the right half plane
Discussion
92.

The transfer function of a system is given as 100 s2 + 20s + 100

A. an overdamped system
B. an underdamped system
C. a critically damped system
D. an unstable system
Answer» D. an unstable system
Discussion
93.

The transfer function of a linear time invariant system is given as

A. 0
B. 0.5
C. 1
D. 2
Answer» C. 1
Discussion
94.

The open loop transfer function of a unity feedback system is given by

A. 11.95 dB
B. 17.67 dB
C. 21.33 dB
D. 23.9 dB
Answer» E.
Discussion
95.

The first two rows of Routh's tabulation of a third order equation are as follows.

A. two roots at s = j and one root in right half s-plane
B. two roots at s = j2 and one root in left half s-plane
C. two roots at s = j2 and one root in right half s-plane
D. two roots at s = j and one root in left half s-plane
Answer» E.
Discussion
96.

The algebraic equation F(s) = s 5 3s 4 + 5s 3 7s 2 + 4s + 20 is given. F(s) = 0 has

A. a single complex root with the remaining roots being real
B. one positive real root and four complex roots, all with positive real parts
C. one negative real root, two imaginary roots, and two roots with positive real parts
D. one positive real root, two imaginary roots, and two roots with negative real parts
Answer» D. one positive real root, two imaginary roots, and two roots with negative real parts
Discussion
97.

A closed-loop syst em has the char acterist ic function (s

A. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-105.jpg">
B. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-106.jpg">
C. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-107.jpg">
D. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-108.jpg">
Answer» C. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-107.jpg">
Discussion
98.

For a system with the transfer function H(s) = 3(s - 2) f, the matrix A4s2 - 2s + 1

A. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-97.jpg">
B. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-98.jpg">
C. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-99.jpg">
D. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-100.jpg">
Answer» C. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/as-99.jpg">
Discussion
99.

If the loop gain K of a negative feedback system having a loop transfer function

A. <table><tr><td rowspan="2"> The frequency of this oscillation must be </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>4</center></td><td rowspan="2"> rad / s</td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">3</span></td></tr></table>
B. The frequency of this oscillation must be must be 4 rad/s
C. <table><tr><td rowspan="2">The frequency of this oscillation must be must be 4 or </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>4</center></td><td rowspan="2"> rad / s</td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">3</span></td></tr></table>
D. such a K does not exist
Answer» E.
Discussion
100.

If x = Re G(j ), and y = lm G(j ) then for 0

A. x = 0
B. <table><tr><td rowspan="2">x = -</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>3</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;">4</td></tr></table>
C. x = y 1 / 6
D. <table><tr><td rowspan="2">x = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>y</center></td><td rowspan="2"> </td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">3</span></td></tr></table>
Answer» C. x = y 1 / 6
Discussion