Time Response Analysis MCQ

61. Consider the network function:

$H(s)=\frac{2(s+3)}{(s+2)(s+4)}$

What is the steady-state response due to a unit step input?

  1. 4/3
  2. 1/2
  3. 3/4
  4. 1
Answer
Answer. c

62. In an RLC series circuit, if the resistance R and the inductance L are kept constant but capacitance C is decreased, then which one of the following statements is/are correct?

  1. Time constant of the circuít is changed.
  2. Damping ratio decreases.
  3. Natural frequency increases.
  4. Maximum overshoot is unaffected.
  1. ii only
  2. i and ii
  3. iii and iv
  4. ii and iii
Answer
Answer. d

63. Consider the following statements in connection with the differential equation given below

$4\frac{\mathrm{d^2}y }{\mathrm{d} t^2}+36y=36x$

  1. The natural frequency of the response is 6 rad/s.
  2. The response is always oscillatory.
  3. The percentage overshoot is 10% and damping ratio of the system is 0.6.
  4. Both system time constant and settling time are infinite.

Which of the statements given above are correct

  1. ii and iv
  2. i and iii
  3. ii, iii and iv
  4. i, ii and iii
Answer
Answer. a

64. The open-loop transfer function of a unity feedback control system is given by $G(s)=\frac{k}{s(s+1)}$. If gain k is increased to infinity, then damping ratio will tend to become

  1. 0.707
  2. zero
  3. Infinite
  4. unity
Answer
Answer. b

65. What are the order and type of closed-loop system for the plant transfer function

$G(s)=\frac{k}{s^2(1+Ts)}$ and with unity feedback?

  1. Two and two
  2. Three and two
  3. Two and zero
  4. Three and zero
Answer
Answer. b

66. Consider the following statements regarding advantages of using the generalized error coefficients:

  1. The generalised error coefficients provide a simple way of determining the nature of the response of a feedback control system to almost any arbitrary input.
  2. The generalised error coefficients lead to the calculation of the steady-state response without actually solving the system differential equation.
  3. The generalised error coefficients establish relationships among the various types of inputs.

Which of the above statements are correct?

  1. i, ii and iii
  2. i and ii
  3. ii and iii
  4. i and iii
Answer
Answer. b

67. The damping ratio and natural frequency of a second-order system are 0.6 and 2 rad/s respectively. Which one of the following combination gives the correct values of peak and settling time, respectively for the unit step response of the system?

  1. 3.33 s and 1.95 s
  2. 1.95 s and 3.33 s
  3. 1.95 s and 1.5 s
  4. 1.5 s and 1.95 s
Answer
Answer. b

68. Which one of the following statement is NOT correct?

  1. With the introduction of integral control, the steady-state error increases.
  2. The generalised error coefficients provide a simple way of determining the nature of the response of feedback control to any arbitrary input.
  3. The generalized error coefficients lead to the calculation of complete steady-state response without actually solving the system differential equation.
  4. For a type-1 system, the steady-state error for acceleration input is infinite.
Answer
Answer. a

69. Consider the following statements with reference to a system with velocity error constant Kv = 1000:

  1. The system is stable.
  2. The system is of type 1.
  3. The test signal used is a step input.

Which of these statements are correct?

  1. i and ii
  2. i and iii
  3. ii and iii
  4. i, ii and iii
Answer
Answer. a

70. If a ramp input is applied to Type-2 system, the steady-state error is

  1. positive constant
  2. negative constant
  3. positive infinity
  4. zero
Answer
Answer. d
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