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ECE :: Automatic Control Systems

  1. Coulomb friction is

  2. A.
    the force of sliding friction between dry surfaces
    B.
    the force of friction between moving surfaces separated by viscous fluid
    C.
    the force required to initiate motion between two contacting surfaces
    D.
    all of the above

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  3. A feedback amplifier has forward gains A1, A2 and feedback factor β as shown in signal flow graph of the given figure. Because of feedback as shown in signal noise ratio at output will

  4. A.
    increase
    B.
    decrease
    C.
    be unaffected
    D.
    depend on value of β

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  5. For the system in the given figure . Then steady state error is

  6. A.
    B.
    K
    C.
    Zero
    D.
    1

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  7. The damping ratio of a pair of complex poles when expressed in terms of angle θ measured from jω axis equal to

  8. A.
    sin θ
    B.
    cos θ
    C.
    tan θ
    D.
    cot θ

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  9. Assertion (A): Derivative control action is also called rate control and has an anticipatory character.

    Reason (R): Derivative control amplifies noise signals.

  10. A.
    Both A and R are correct and R is correct explanation of A
    B.
    Both A and R are correct but R is not correct explanation of A
    C.
    A is correct but R is wrong
    D.
    R is correct but A is wrong

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  11. Assertion (A): When a PID controller is added to a system, the peak overshoot to step input cannot be determined easily.

    Reason (R): Use of PID controller introduces a zero in the forward path.

  12. A.
    Both A and R are correct and R is correct explanation of A
    B.
    Both A and R are correct but R is not correct explanation of A
    C.
    A is correct but R is wrong
    D.
    R is correct but A is wrong

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  13. For the system shown in the given figure the time response to unit step input is

  14. A.
    B.
    c(t) = T(1 - e-t/T)
    C.
    c(t) = 1 - e-t/T
    D.
    c(t) = T e-t/T

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  15. The slope of log magnitude asymptote changes by - 40 dB/ decade at a certain frequency and the error between asymptote and actual curve is - 6 dB. This means that

  16. A.
    a double pole is present
    B.
    a pair of complex conjugate poles is present
    C.
    either a double pole or a pair of complex conjugate poles is present
    D.
    either a pole or zero at that frequency is present

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  17. Friction forces acts in a direction

  18. A.
    opposite to that of velocity
    B.
    same as that of velocity
    C.
    at right angle to that of velocity
    D.
    partly opposite and partly at right angle to the direction of velocity

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  19. Assertion (A): Integral control action is sometimes called reset control.

    Reason (R): Reset rate is expressed as number of repeats per unit time.

  20. A.
    Both A and R are correct and R is correct explanation of A
    B.
    Both A and R are correct but R is not correct explanation of A
    C.
    A is correct but R is wrong
    D.
    R is correct but A is wrong

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