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ECE :: Exam Questions Paper

  1. A lossless 50 Ω transmission line is terminated 30 + j25 Ω, then voltage reflection coefficient and current reflection coefficient are

  2. A.
    062 ∠82.88, - 0.62 ∠82.88
    B.
    10.36 ∠11.296, - 10.36 ∠111.296
    C.
    0.23 ∠49.1, - 0.23 ∠ + 49.1
    D.
    - 10.36 ∠111.296, 10.36 ∠111.296

  3. Find value of i

  4. A.
    1A
    B.
    0A
    C.
    0.45 A
    D.
    None of these

  5. The circuit shown in the figure has 4 boxes each described by inputs P, Q, R and outputs Y, Z with
    Y = P ⊕ Q ⊕ R, Z = RQ + P R + Q P

    The circuit is a

  6. A.
    4 bit adder giving P + Q
    B.
    4 bit subtractor giving P - Q
    C.
    4 bit subtractor giving Q - P
    D.
    4 bit adder giving P + Q + R

  7. Find the electric charge required on the earth and moon to balance their gravitational attraction if the charge on the earth is 12.5 times that on the moon.
    Mass of moon = 6.7 x 1022 Kg
    Mass of earth = 6 x 1024 Kg
    Distance between moon and earth = 380 Km
    Universal gravitational constant = 6.7 x 10-11 Nm2/Kg2

  8. A.
    48.9 TC
    B.
    4.89 GC
    C.
    4.89 TC
    D.
    48.9 GC

  9. When x(n) is real then the Fourier series coefficients are correlated as __________ .

  10. A.
    a-k = ak*
    B.
    ak = ak*
    C.
    ak+1 = ak*
    D.
    a-k+1 = ak*

  11. A lossless transmission line with air dielectric is 6 m long. What is the line length at 30 MHz?

  12. A.
    1 wavelength long
    B.
    0.5 wavelength long
    C.
    0.6 wavelength long
    D.
    0.25 wavelength long

  13. Given that F(s) is the one-sided Laplace transform of f(t), the Laplace transform of f(t)dt is

  14. A.
    sFs - f(0)
    B.
    C.
    F(t)dt
    D.

  15. The antenna current of an AM broad cast transmitter, modulated to a depth of 40% by an audio sine wave is 11 amperes. It increased to 12 ampere as a result of simultaneous modulation by another sine wave. The modulation index due to this second sine wave is :

  16. A.
    0.4
    B.
    0.757
    C.
    0.643
    D.
    0.8

  17. Two D flip-flop as shown below are to be connected as a synchronous counter that goes through the following Q1Q0 sequence
    00 → 01 → 11 → 10 → 00 → __________
    The inputs D0 and D1 respectively should be connected as

  18. A.
    Q1 and Q0
    B.
    Q0 and Q1
    C.
    Q1 Q0 and Q1 Q0
    D.
    Q1 Q0 and Q1 Q0

  19. The z-transform of a signal is given by . Its final value is :

  20. A.
    1/4
    B.
    zero
    C.
    1
    D.
    infinity