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ECE :: Electronic Devices and Circuits

  1. In LED the radiation is in

  2. A.
    visible region
    B.
    infrared region
    C.
    both (a) and (b)
    D.
    neither (a) nor (b)

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  3. The rate of change of excess carrier density is proportional to carrier density.

  4. A.
    True
    B.
    False

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  5. Tuned voltage amplifiers are not used

  6. A.
    radio receivers
    B.
    public address system
    C.
    T.V. Receivers
    D.
    band of freq. selected and amplified

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  7. The main reason why Ni-Zn ferrites are used for audio and T.V. transformers is that

  8. A.
    they have large saturation magnetization
    B.
    they are easy to fabricate by rolling
    C.
    they are totally free from pores and voids
    D.
    they have a high electrical resistivity

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  9. Assertion (A): Intrinsic semiconductor is an insulator at 0 K.

    Reason (R): Fermi level in intrinsic semiconductor is in the centre of forbidden energy band.

  10. A.
    Both A and R are true and R is correct explanation of A
    B.
    Both A and R are true but R is not a correct explanation of A
    C.
    A is true but R is false
    D.
    A is false but R is true

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  11. Typical values of h parameters at about 1 mA collector current for small signal audio amplifier in CE configuration are :

  12. A.
    hie = 100 Ω, hre = 10-1, hfe = 50, hoe = 1 m mho
    B.
    hie = 5 kΩ, hre = 10-4, hfe = 200, hoe = 20 m mho
    C.
    hie = 5 kΩ, hre = 0, hfe = 50, hoe = 2 m mho
    D.
    hie = 100 kΩ, hre = 10-2, hfe = 100, hoe = 10 m mho

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  13. A CMOS amplifier when compared to an N-channel. MOSFET, has the advantage of

  14. A.
    higher cut off frequency
    B.
    higher voltage gain
    C.
    higher current gain
    D.
    lower current drain from the power supply, there by less dissipation

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  15. Dynamic resistance of diode is

  16. A.
    True
    B.
    False

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  17. The presence of some holes in an intrinsic semiconductor at room temperature is due to

  18. A.
    valence electrons
    B.
    doping
    C.
    free electrons
    D.
    thermal energy

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