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ECE :: Electronic Devices and Circuits

  1. Lowest resistivity of the following is

  2. A.
    constantan
    B.
    german silver
    C.
    manganin
    D.
    nichrome

  3. Peak inverse voltage will be highest for

  4. A.
    half wave rectifier
    B.
    full wave rectifier
    C.
    bridge rectifier
    D.
    three phase full wave rectifier

  5. In CE configuration, the output characteristics of a bipolar junction transistor is drawn between

  6. A.
    IC and VCB
    B.
    IE and VCB
    C.
    IC and VCE
    D.
    IE and VCE

  7. Assertion (A): The reverse current in a p-n junction is nearly constant.

    Reason (R): The reverse breakdown voltage of a p-n diode depends on the extent of doping.

  8. 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

  9. An n type semiconductor is illuminated by a steady flux of photons with energy greater than the band gap energy. The change in conductivity Δσ obeys which relation?
    [ Here, e is the electron charge, μn electron mobility, μp hole mobility, Δnp) is the excess electron (hole) density ].

  10. A.
    Δσ = 0
    B.
    Δσ = en + σp) Δn
    C.
    Δσ = enΔn - μpΔp)
    D.
    Δσ = e μnΔn

  11. Resistivity of metals is expressed in terms of

  12. A.
    μ ohm
    B.
    μ ohm/cm
    C.
    μ ohm-cm
    D.
    μ ohm-cm/°C

  13. Figure shows characteristics curves for bipolar transistor. These curves are

  14. A.
    output characteristics of n-p-n transistor (common base)
    B.
    output characteristics of p-n-p transistor (common base)
    C.
    output characteristics of n-p-n transistor (common emitter)
    D.
    output characteristics of p-n-p transistor (common emitter)

  15. Zener diode is invariably used with

  16. A.
    forward bias
    B.
    reverse bias
    C.
    either (a) or (b)
    D.
    zero bias

  17. The relation between plate current and plate voltage of a vacuum diode is called

  18. A.
    Richardson Dushman equation
    B.
    Langmuir Child law
    C.
    Ohm's law
    D.
    Boltzmann's law

  19. Given that the band gap of cadmium sulphide is 2.5 eV, the maximum photon wavelength, for e--hole pair generation will be

  20. A.
    5400 mm
    B.
    540 mm
    C.
    5400 Å
    D.
    540 Å