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ECE :: Electronic Devices and Circuits

  1. A particular green LED emits light of wavelength 5490, Å, the energy bandgap of the semiconductor material used there is .. h = 6.6 x 10-34 J sec.

  2. A.
    2.26 eV
    B.
    1.98 eV
    C.
    1.17 eV
    D.
    0.74 eV

  3. In a zener diode

  4. A.
    the forward current is very high
    B.
    sharp breakdown occurs at a certain reverse voltage
    C.
    the ratio v-i can be negative
    D.
    there are two p-n junctions

  5. In a bipolar transistor which current is largest

  6. A.
    collector current
    B.
    base current
    C.
    emitter current
    D.
    base current or emitter current

  7. The v-i characteristics of a FET is shown in figure. In which region is the device biased for small signal amplification

  8. A.
    AB
    B.
    BC
    C.
    CD
    D.
    BD

  9. Secondary emission is always decremental.

  10. A.
    True
    B.
    False

  11. In a degenerate n type semiconductor material, the Fermi level,

  12. A.
    is in valence band
    B.
    is in conduction band
    C.
    is at the centre in between valence and conduction bands
    D.
    is very near valence band

  13. The types of carriers in a semiconductor are

  14. A.
    1
    B.
    2
    C.
    3
    D.
    4

  15. Assertion (A): The reverse saturation current in a semiconductor diode is 4nA at 20°C and 32 nA at 50°C.

    Reason (R): The reverse saturation current in a semiconductor diode doubles for every 10°C rise in temperature.

  16. 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

  17. Calculate the stability factor and change in IC from 25°C to 100°C for, β = 50, RB/ RE = 250, ΔIC0 = 19.9 nA for emitter bias configuration.

  18. A.
    42.53, 0.85 μA
    B.
    40.91, 0.58 μA
    C.
    40.91, 0.58 μA
    D.
    41.10, 0.39 μA

  19. A periodic voltage has following value for equal time intervals changing suddenly from one value to next... 0, 5, 10, 20, 50, 60, 50, 20, 10, 5, 0, -5, -10 etc. Then rms value of the waveform is

  20. A.
    31 V
    B.
    32 V
    C.
    insufficient data
    D.
    none of these