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ECE :: Signals and Systems

  1. A voltage v = 5 + 50 sin ωt/ + 5 sin 5 &omegat is applied to a pure capacitor of capacitance 1 ωF. If f/= 314 rad/sec, current is

  2. A.
    1 + 0.0157 cos 314 t + 0.00785 cos 1570 t
    B.
    0.0157 cos 314 t + 0.00785 cos 1570 t
    C.
    0.0157 sin 314 t + 0.00785 sin 1570 t
    D.
    0.0157 sin (314 t / + 45°) + 0.00785 sin (1570 t + 45°)

  3. The stationary process has

  4. A.
    all the statistical Properties dependent on time.
    B.
    all the statistical Properties independent of time.
    C.
    aime average is equal to ensemble average.
    D.
    zero variance.

  5. If x1(t) = 2 sin pt + cos 4 pt and x2(t) = sin 5 pt + 3 sin 13 pt then

  6. A.
    x1, x2 both periodic
    B.
    x1 x2 both not periodic
    C.
    x1 periodic, x2 not periodic
    D.
    x1 is not periodic ; but x2 is periodic

  7. An ac network has a power factor of 0.8 leading if the applied wave is of fundamental frequency. If the applied wave contains third and fifth harmonics, the overall power factor will be

  8. A.
    0.8 leading
    B.
    less than 0.8 leading
    C.
    more than 0.8 leading
    D.
    0.8 leading or more

  9. Assertion (A): A sweep circuit operates by virtue of recurring transient phenomenon.

    Reason (R): Transients are always undesirable.

  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 true, R is false
    D.
    A is false, R is true

  11. If f(t) = - f(- t) satisfies Drichlet conditions, then f(t) can be expanded in Fourier series containing

  12. A.
    only sine terms
    B.
    only cosine terms
    C.
    cosine terms and constant
    D.
    sine terms and constant

  13. The joint probability function of two discrete random variable X and Y is given by
    x = 0, 2, y = 2, 3 then E(y) is


  14. The joint probability function of two discrete random variable X and Y is given by
    x = 0, 2, y = 2, 3 variance σ2 will be
    [Hint: σ2 = E(X2) - μ2 ⇒ E(X2) - (E(X))2]

  15. A.
    B.
    C.
    D.
    zero

  16. A probability density function is given by p(x) = Ke-x2/2 for -∞ < x < ∞ , The value of K should be


  17. The Laplace transform of f(t) is

  18. A.
    B.
    C.
    D.
    none of the above