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ECE :: Exam Questions Paper

  1. In the following non planar graph number of independent loop equations are

  2. A.
    8
    B.
    12
    C.
    7
    D.
    5

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  3. A transmission line has a characteristic impedance of 50 Ω and a resistance of 0.1 Ω/m, if the line is distortion less, the attenuation constant (in Np/m) is

  4. A.
    500
    B.
    5
    C.
    0.014
    D.
    0.002

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  5. A certain 8 bit uniform quantization PCM system can accommodate a signal ranging from - 1 V to + V. The rms value of the signal is V . The signal to quantization noise ratio is:

  6. A.
    30 dB
    B.
    46.91 dB
    C.
    40 dB
    D.
    49.92 dB

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  7. A rectangular waveguide, in dominant TE mode, has dimensions 10 cm x 15 cm. The cut off frequency is

  8. A.
    10 GHz
    B.
    1 GHz
    C.
    15 GHz
    D.
    25 GHz

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  9. A radar receiver has a noise figure of 10 dB at 300 K having a bandwidth of 2.5 MHz. The minimum power it can receive is

  10. A.
    3.45 x 10-15 W
    B.
    1.38 x 10-15 W
    C.
    7.5 x 10-15 W
    D.
    93.15 x 10-15 W

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  11. In the circuit shown, in switch S is open for a long time and is closed at t = 0. The current i(t) for t ≥ 0+ is

  12. A.
    i(t) = 0.5 - 0.125e-1000t A
    B.
    i(t) = 1.5 - 0.125e-1000t A
    C.
    i(t) = 0.5 - 0.5e-1000t A
    D.
    i(t) = 0.375e-1000t A

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  13. In a semiconductor material. The hole concentration is found to be 2 x 2.5 x 1015 cm-3. If mobility of carriers is 0.13 m2/ v-s. Then find the current density if electric field intensity is 3.62 x 10-19

  14. A.
    7.6237 x 10-4 A/cm2
    B.
    7.6237 x 10-5 A/cm2
    C.
    7.6237 x 10-3 A/cm2
    D.
    none of these

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  15. Consider the system with and where p and q are arbitrary real numbers. Which of the following statements about the controllability of the system is true?

  16. A.
    The system is completely state controllable for any non zero values p and q
    B.
    Only p = 0 and q = 0 result in controllability
    C.
    The system is uncontrollable for all values of p and q
    D.
    We cannot conclude about controllability from the given data

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  17. A MOSFET has a threshold voltage of 1 V and oxide thickness of 500 x 10-8r = 3.9; ε0 = 8.85 x 10-14 F/cm, q = 1.6 x 10-19 c]. The region under the gate is ion implanted for threshold voltage tailoring. The base and type of impant required to shift threshold voltage to - 1 V are __________ .

  18. A.
    8.6 x 1011/cm2, p-type
    B.
    8.6 x 1011/cm2, n-type
    C.
    0.86 x 109/cm2, p-type
    D.
    1.02 x 1012/cm2, n-type

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  19. What is the propagation constant for air filled wave guide with dimensions a = 1.59" and b = 0.795" at 4.95 GHz?

  20. A.
    0.6698
    B.
    0.7698
    C.
    0.503
    D.
    0.6598

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