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ECE :: Electronic Devices and Circuits

  1. The number of valence electrons in a donor atom is

  2. A.
    2
    B.
    3
    C.
    4
    D.
    5

  3. An electron rises through a voltage of 100 V. The energy acquired by it will be

  4. A.
    100 eV
    B.
    100 joules
    C.
    (100)1.2 eV
    D.
    (100)1.2 joules

  5. Measurement of hall coefficient enables the determination of

  6. A.
    mobility of charge carriers
    B.
    type of conductivity and concentration of charge carriers
    C.
    temperature coefficient and concentration of charge carriers
    D.
    fermi level and forbidden energy gap

  7. A Varactor diode has

  8. A.
    a fixed capacitance
    B.
    a fixed inductance
    C.
    a voltage variable capacitance
    D.
    a current variable inductance

  9. The most important set of specifications of transformer oil includes

  10. A.
    dielectric strength and viscosity
    B.
    dielectric strength and flash point
    C.
    flash point and viscosity
    D.
    dielectric strength, flash point and viscosity

  11. Assertion (A): In Hall effect the O.C. transverse voltage developed by a current carrying semiconductor with a steady magnetic field perpendicular to the current direction has opposite signs for n and p semiconductors.

    Reason (R): The magnetic field pushes both holes and electrons in the same direction.

  12. 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

  13. A voltage of 9 V is applied in forward direction to a semiconductor diode in series with a load resistance of 1000 Ω. The voltage across the load resistance is zero. It indicates that

  14. A.
    diode is short circuited
    B.
    diode is open circuited
    C.
    resistor is open circuited
    D.
    diode is either o.c or s.c

  15. If the drift velocity of holes under a field gradient of 100 V/m in 5 m/s, their mobility (in SI units) is

  16. A.
    0.05
    B.
    0.5
    C.
    50
    D.
    500

  17. The derating factor for a BJT transistor is about

  18. A.
    0.5 mW/°C
    B.
    2.5 mW/°C
    C.
    10 mW/°C
    D.
    25 mW/°C

  19. An intrinsic silicon sample has 2 million free electrons. The number of holes in the sample is

  20. A.
    2 million
    B.
    almost zero
    C.
    more than 2 million
    D.
    less than 2 million