1. A linear time invariant system initially at rest, when subjected to a unit-step input, gives a response
y(t)=te-t; t>0. The transfer function of the system is
𝑠
1
1
1
𝐶.
𝐴.
B.
D.
(
(
(
(𝑠 + 1)
(𝑠 + 1)
𝑠(𝑠 + 1)
𝑠(𝑠 + 1)
Ans A
2. The series RLC circuit shown in figure is underdamped if
A.
B.
C.
* (
(+
* (
(+
* (
(+
<
=
>
+.
+.
+.
D. None of a, b and c are correct
Ans A
3. The plot in figure shows the unit step response of a first
order system. Transfer function of the system is
A.
B.
C.
D.
123(
-123(
423-123-
Ans C
4. For open loop control system which of the following statements is incorrect?
A. Less expensive
B. Recalibration is not required for maintaining the required quality of the output
C. Construction is simple and maintenance is easy
D. Errors are caused by disturbances
Ans B
5. _____ system has tendency to oscillate
A. open loop system
B. b. closed loop system
C. c. both a and b
D. d. neither a nor b
Ans B
6. An automatic toaster is a _______ loop control system.
A. Open b. closed c. partially closed d. any of the above
Ans A
7. Which of the following is exhibited by Root Locus diagram?
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. None of the above
Ans A
8. If the gain of the critically damped system is increased it will behave as
A. Undamped B. overdamped C. underdamped D. none of the above
Ans C
9. A signal other than the reference input that tends to affect the value of controlled variable is known
as: A. disturbance B. command C. control element D. None of the above
Ans A
10. Transfer function of a system is used to calculate which of the following?
A. System order B. time constant C. output for any given input D. steady state gain
Ans C
11. Basically, poles of the transfer function are the Laplace transform variable values which causes the
transfer function to become _____
A. Zero B. Unity C. Infinite D. Average value
Ans C
12. The transfer function R(s) to Y(s) of the system of figure is
Ans C
13. A unity feedback system has open-loop transfer function 𝐺 𝑠 =
6(23-)(23()
2(234)(237)
. For K=10, the closed
loop poles are
A. All real and distict
B. One real and two complex conjugate
C. All real and repeated
D. None of the answers in A, B and C is correct
Ans A
14. The bode asymptotic plot of a transfer function is given
in figure. The transfer function has
A. One pole and one zero
B. Two poles and one zero
C. One pole and two zeros
D. None of the above
Ans C
15. Consider the root locus plot of unity-feedback system with open loop transfer function
The break away point of the root-loci on the real axis occurs at
A. -3
B. -4.5
C. -5.5
D. None of the above
Ans. D
16. A unity feedback system with open loop transfer function 𝐺 𝑠 =
value of the parameter P is
A. 4
B. 3
C. 2
7
[2 239 ]
is critically damped. The
D. 1
Ans. A
17. Which of the following describes the step response of the closed loop system of figure?
A. Underdamped
B. Critically damped
C. Overdamped
D. The output does not reach a steady-state value
Ans A
18. The first two rows of a Routh Table of a third order system is are
A.
B.
C.
D.
The characteristic equation has one root in right half s-plane
The characteristic equation has two roots on the 𝑗𝜔 axis at 𝑠 = ±𝑗
The characteristic equation has two roots on the 𝑗𝜔 axis at 𝑠 = ±𝑗2
None of the answers of A, B and C is correct
Ans B
19. A unity feedback system has open loop transfer function G(s). Bode
plot of G(j𝜔) is shows in figure. The feedback system has
A. Positive phase margin and negative gain margin
B. Positive phase margin and positive gain margin
C. Negative phase margin and negative gain margin
D. Positive phase margin and positive gain margin
Ans B
20. The main equation of a Nyquist Stability Criterion is Z=P-N. What is Z?
A. Number of zeroes of closed loop transfer function
B. Number of zeros of G(s)H(s)
C. Number of poles of 1+G(s)H(s)
D. Number of poles of closed loop transfer function
Ans D.