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ECE :: Electronic Devices and Circuits

  1. An increase in junction temperature of a semiconductor diode

  2. A.
    causes a small increase in reverse saturation current
    B.
    causes a large increase in reverse saturation current
    C.
    does not affect reverse saturation current
    D.
    may cause an increase or decrease in reverse saturation current depending on rating of diode

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  3. An air gap provided in the iron core of an inductor prevents

  4. A.
    flux leakage
    B.
    hysteresis loss
    C.
    core saturation
    D.
    heat generation

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  5. Generally, the gain of a transistor amplifier falls at high frequency due to the

  6. A.
    internal capacitance of the device
    B.
    coupling capacitor at the I/P
    C.
    skin effect
    D.
    coupling capacitor at the O/P

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  7. Which of these has a layer of intrinsic semiconductor?

  8. A.
    Zener diode
    B.
    PIN diode
    C.
    Photo diode
    D.
    Schottky diode

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  9. Assertion (A): When Diode used as rectifier the reverse breakdown voltage should not be exceeded.

    Reason (R): A high inverse voltage can destroy a p-n junction.

  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. A Si sample is doped with a fixed number of group N impurities. The electron density n is measured from 4 K to 1200 k for the sample. Which one of the following is correct?

  12. A.
    n remains constant over the temperature range
    B.
    n increases monotonicaliy with increasing temp
    C.
    n increases first remains constant over a range and again increases with increasing temperature
    D.
    n increases show a peak and then decrease with temperature

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  13. Assertion (A): In design of circuit using BJT, a derating factor is used.

    Reason (R): As the ambient temperature increases, heat dissipation becomes slower.

  14. 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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  15. If the drift velocity of holes under a field gradient of 100 V/m is 5m/sec. Their mobility is

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

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  17. In a P type silicon sample, the hole concentration is 2.25 x 1015 / cm3. If the intrinsic carrier concentration is 1.5 x 1010/ cm3 the electron concentration is

  18. A.
    zero
    B.
    1010/cm3
    C.
    105/cm3
    D.
    1.5 x 1025/cm3

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  19. The behaviour of a JFET is similar to that of

  20. A.
    NPN transistor
    B.
    PNP transistor
    C.
    SCR
    D.
    Vacuum triode

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