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ECE :: Exam Questions Paper

  1. Which one of the following type of negative feedback increases the input resistance and decreases the output resistance of an amplifier?

  2. A.
    Current series feedback
    B.
    Voltage series feedback
    C.
    Current shunt feedback
    D.
    Voltage shunt feedback

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  3. A load ZL = RL + jXL is to be matched using an ideal transformer to generator of internal impedance ZS = RS + jXS. The ratio of transformer required is __________ .

  4. A.
    |ZS|/|ZL|
    B.
    RL/RS
    C.
    RL/ZS
    D.
    |ZL|/RS

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  5. An AC source or RMS voltage 20V with internal impedance Zs = (1 + 2j) Ω feeds a load of impedance ZL = (7 + 4j) Ω in the figure below. The reactive power consumed by the load is

  6. A.
    8 VAR
    B.
    16 VAR
    C.
    28 VAR
    D.
    32 VAR

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  7. Electric dipole is located at origin in a medium with εr = 6, has a moment P = (4ax - 2ay + az ) nC. Then potential at (2, 4, 4) is:

  8. A.
    0.062
    B.
    0.027
    C.
    0.042
    D.
    0.072

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  9. Voice signal band limited to 3.4 KHz is sampled and pulse code modulated using 64 quantization levels. Ten such signals are time division multiplexed using one 5-bit synchronizing word every alternate frame. The minimum channel bandwidth required for transmission of the TDM signal is

  10. A.
    100 KHz
    B.
    200 KHz
    C.
    50 KHz
    D.
    150 KHz

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  11. Which of the following is/are correct statement(s)?

    1. Bus is a group of wires carrying information.
    2. Bus is needed to achieve reasonable speed of operation.
    3. Bus can carry data or address.
    4. A bus can be shared by more than one device.
    Select the correct answer from the codes given below

  12. A.
    1 only
    B.
    1 and 2 only
    C.
    2, 3 and 4 only
    D.
    1, 2, 3 and 4

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  13. Assertion (A): A fixed bias BJT circuit exhibits better performance as compared to a self bias BJT circuit.

    Reason (R): A fixed bias BJT circuit used less components as compared to a self bias BJT circuit.

  14. A.
    Both A and R are individually true and R is the correct explanation of A
    B.
    Both A and R are individually true but R is not the correct explanation of A
    C.
    A is true but R is false
    D.
    A is false but R is true

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  15. A linear time-invariant, causal continuous time system has a rational transfer function with simple poles at s = - 2 and s = - 4, and one simple zero at s = - 1. A unit step u(t) is applied at the input of the system. At steady state, the output has constant value of 1. The impulse response of this system is

  16. A.
    [exp (- 2t) + exp (-4t)] u(t)
    B.
    [-4 exp (- 2t) + 12 exp (-4t) - exp (-t)] u(t)
    C.
    [-4 exp (- 2t) + 12 exp (-4t)] u(t)
    D.
    [-0.5 exp (- 2t) + 1.5 exp (-4t)] u(t)

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  17. The signal cos ωct + 0.5 cos ωmt sin ωct is

  18. A.
    FM only
    B.
    AM only
    C.
    both AM & FM
    D.
    neither AM nor FM

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  19. Which one of the following is a transferred electron device?

  20. A.
    BARITT diode
    B.
    IMPATT diode
    C.
    TRAPATT diode
    D.
    Gunn diode

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