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Quiz: Time Domain Analysis-LCS

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Number of Questions: 20

Question: 11 -

The output in response to a unit step input for a particular continuous control system is c(t)= 1-e-t. What is the delay time Td?

Options:

  1. 0.18

  2. 0.36

  3. 0.693

  4. 0.289

    5. Answer:

    0.693
    Solution:

    Explanation: The output is given as a function of time. The final value of the output is limn->∞c(t)=1; . Hence Td (at 50% of the final value) is the solution of 0.5=1-e-Td, and is equal to ln 2 or 0.693 sec.

Question: 12 -

Laplace transform of unit impulse signal is :

Options:

  1. A

  2. 1/s

  3. 1

  4. A/s

    5. Answer:

    1
    Solution not available.

Question: 13 -

The damping ratio and peak overshoot are measures of:

Options:

  1. Speed of response

  2. Absolute stability

  3. Steady state error

  4. Relative stability

    5. Answer:

    Speed of response
    Solution not available.

Question: 14 -

The forward path transfer function is given by G(s) = 2/s(s+3). Obtain an expression for unit step response of the system.

Options:

  1. 1-2e-t+e+2t

  2. 1-e-t+2e-2t

  3. 1+e-t-2e-2t

  4. 1+2e-t+e-2t

    5. Answer:

    1-2e-t+e+2t
    Solution:

    C(s)/R(s) = s/(s2+3s+2)
    C(s) = 1/s-2/s+1+1/s+2
    c(t) = 1-2e-t+e+2t.

Question: 15 -

For the system 2/s+1, the approximate time taken for a step response to reach 98% of its final value is:

Options:

  1. 8s

  2. 2s

  3. 1s

  4. 4s

    5. Answer:

    4s
    Solution:

    C(s)/R(s) = 2/s+1
    R(s) = 1/s (step input)
    C(s) = 2/s(s+1)
    c(t) = 2[1-e-t] 1.96 = 2[1-e-T] T= 4sec.