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ECE :: Signals and Systems

  1. A signal is sampled at Nyquist rate fs = 2f0. The function can be recovered from its samples only. If it is a

  2. A.
    Periodic square wave of fundamental frequency f0
    B.
    Triangular wave of fundamental frequency f0
    C.
    Periodic sine wave of fundamental frequency f0
    D.
    Unit impulse function

  3. A voltage wave is v = 50 sin ωt. Its average value calculated over full one cycle is

  4. A.
    zero
    B.
    35.36 V
    C.
    31.85 V
    D.
    none of the above

  5. If f1 (t) and f2 (f) are two functions of time and a and b are constants, then

  6. A.
    L [af1(t) + bf2(t)] = aF1(s) + bF2(s)
    B.
    L [af1(t) + bf2(t)] = aF1(s) - bF2(s)
    C.
    L [af1(t) + bf2(t)] =[aF1(s)]/[bF2(s]
    D.
    None of the above

  7. The z transform of x(n) = ∪(n)


  8. Fourier transform of f(t) =

  9. A.
    jω F(f)
    B.
    2pf F(f)
    C.
    F'(f)
    D.
    None

  10. A voltage wave is i = 100 sin (ωt). Its average value calculated over one half cycle is

  11. A.
    zero
    B.
    70.72 V
    C.
    63.70 V
    D.
    none of the above

  12. In the given figure 15.5 show a discrete time system consisting of a unit delay system, a multiplier and a summer, such that y(k) = x(k - 1) + 0.5 x(k). This system

  13. A.
    is linear
    B.
    is non linear
    C.
    may be linear or non linear depending on value
    D.
    impossible to judge

  14. An RLC series circuit has a variable inductance. The value of L for resonance conditions at fundamental frequency is 0.18 H. For resonance conditions at third harmonic frequency the value of inductance is

  15. A.
    0.54 H
    B.
    0.06 H
    C.
    0.02 H
    D.
    1.62 H

  16. which of the following is not correct?

  17. A.
    P(A) = P(A) - 1
    B.
    0 ≤ P ≤ 1
    C.
    If A and B are mitual exclusive then P(A + B) = P(A) + P(B)
    D.
    P(A) = 1 - P(A)

  18. If function f(t) has an initial value f(0-) at t = 0-, the Laplace transform of is

  19. A.
    sF(s) - f(0-)
    B.
    sF(s) + f(0-)
    C.
    s2F(s) - f(0-)
    D.
    s2F(s) + f(0-)