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ECE :: Exam Questions Paper

  1. A speech signal, band limited to 4kHz and peak voltage varying between + 5V and - 5V is sampled at the Nyquist rate. Each sample is quantized and represented by 8 bits. Assuming the signal to be uniformly distributed between its peak values, the signal to noise ratio at the quantizer output is

  2. A.
    156 dB
    B.
    32 dB
    C.
    48 dB
    D.
    64 dB

  3. The drain current of a MOSFET in saturation is given by lp = K(VGS - VT)2 where K is a constant. The magnitude of the transconductance gm is

  4. A.
    B.
    2K (VGS - VT)
    C.
    D.

  5. Two infinitely long wires carrying current are as shown in the figure below. One wire is in the y-z plane and parallel to the y-axis. The other wise is in the x-y plane and parallel to the x-axis. Which components of the resulting magnetic field are non-zero at the origin?

  6. A.
    x, y, z components
    B.
    x, y components
    C.
    y, z components
    D.
    x, z components

  7. A uniform plane wave is described by the equation H = A/m. If the velocity of the wave is 2 x 108 m/s and εr = 1.8, then. The electric field intensity is

  8. A.
    90.35e-j0.1px v/m
    B.
    903.5e-j0.1px v/m
    C.
    903.5e-j0.1pz v/m
    D.
    90.35e-j0.1pz v/m

  9. The amplitude modulated wave is given by __________ e = 25(1 + 0.7 cos 5000t - 0.3 cos 1000t) x sin 5 x 106t The amplitude of carrier and sideband frequencies in magnitudes are

  10. A.
    25, 0.7, 0.3
    B.
    25, 0.7, - 0.3
    C.
    24, 17.5, 7.5
    D.
    25, 8.75, 3.75

  11. A signal flow graph of a system is given below

    The set of equations that correspond of this signal flow graph is


  12. (11)2 + (11)3 = (11)?

  13. A.
    4
    B.
    5
    C.
    6
    D.
    not possible

  14. If h1[n] = 3δ[n] + δ[n - 1], h2[n] = 2δ[n] + δ[n - 2]
    h3[n] = δ[n] - 3δ[n - 1] + 7δ[n - 4] + 6δ[n - 6]
    h[n] = h1[n] * h2[n] + h3[n] * h1[n] has value

  15. A.
    {6, 18, 7, 4, 0, - 6, 9}
    B.
    {9, 0, - 6, 21, 7, 6, 1}
    C.
    {7, - 1, 3, 1, 7, 0, 6}
    D.
    {9, - 6, 0, 1, 21, 7, 18, 6}

  16. The feedback control system shown in the given figure represents

  17. A.
    Type 0 system
    B.
    Type 1 system
    C.
    Type 2 system
    D.
    Type 3 system

  18. Time domain equivalent circuit of the figure is

  19. A.
    B.
    C.
    D.
    None of the above