power-electronics-mcqs - Set (1)

Correct Answer: Orange && Worng Answer: Red

1. In a thyristor, anode current is made of

  • (A). Electrons only
  • (B). Electrons or holes
  • (C). Electrons and holes
  • (D). None of these
    • View Answer

    Explanation: Not Avilable

    2. A DIAC can be terned as :

  • (A). Diode AC Switch
  • (B). TRIODE AC Switch
  • (C). Both (a) and (b)
  • (D). None of the above
    • View Answer

    Explanation: Not Avilable

    3. A UJT exhibits negative resistance region :

  • (A). Before the peak point
  • (B). Between peak and valley points
  • (C). After the valley point
  • (D). Both (a) and (c)
    • View Answer

    Explanation: Not Avilable

    4. Inverter converts :

  • (A). DC to AC
  • (B). AC to DC
  • (C). Both (a) and (b)
  • (D). None of the above
    • View Answer

    Explanation: Not Avilable

    5. Which semiconductor device behaves structurally as consisting of a diode and two resistors :

  • (A). UJT
  • (B). TRIAC
  • (C). SCR
  • (D). Shockley diode
    • View Answer

    Explanation: Not Avilable

    6. AC power in a load can be controlled by using :

  • (A). Two SCRs in parallel opposition
  • (B). Two SCRs in series
  • (C). Three SCRs in series
  • (D). Four SCRs in series
    • View Answer

    Explanation: Not Avilable

    7. In a full wave rectifier, the rectification ratio is approximately equal to :

  • (A). 61%
  • (B). 71%
  • (C). 81%
  • (D). 91%
    • View Answer

    Explanation: Not Avilable

    8. The p-type emitter of a UJT is ______ dopped.

  • (A). Lightly
  • (B). Moderately
  • (C). Heavily
  • (D). Not
    • View Answer

    Explanation: Not Avilable

    9. For an SCR, di/dt protection is achieved through the use of

  • (A). R in series with SCR
  • (B). RL in series with SCR
  • (C). L in series with SCR
  • (D). L across SCR
    • View Answer

    Explanation: Not Avilable

    10. In a pulse width modulation of chopper :

  • (A). T is kept constant & TON is changed
  • (B). TON is kept constant and T is changed
  • (C). Both T and TON are changed
  • (D). Either T or TON is changed
    • View Answer

    Explanation: Not Avilable

    11. Choppers can be used to

  • (A). Increase a DC voltage
  • (B). Decrease a DC voltage
  • (C). Increase or decrease a DC voltage
  • (D). None of these
    • View Answer

    Explanation: Not Avilable

    12. A single-phase full converter operates as an inverter, when

  • (A). 0° ≤ α ≤ 90°
  • (B). 90° ≤ α ≤ 180°
  • (C). It supplies to a back emf load
  • (D). 90° ≤ α ≤ 180° and there is a suitable DC source in the load circuit
    • View Answer

    Explanation: Not Avilable

    13. The average value of the output voltage in a step down DC chopper is given by :

  • (A). Vo = Vs
  • (B). Vo = KVs
  • (C). Vo = Vs/K
  • (D). Vo = Vs/(1-K)
    • View Answer

    Explanation: Not Avilable

    14. The control method used for PWM DC-DC converter is

  • (A). Voltage mode control
  • (B). Current mode control
  • (C). Hysteric control
  • (D). All of these
    • View Answer

    Explanation: Not Avilable

    15. A fully controlled converter uses :

  • (A). Diodes only
  • (B). Thyristors only
  • (C). Both diodes and thyristor
  • (D). Insufficient data
    • View Answer

    Explanation: Not Avilable

    16. Which device can be used in chopper circuit :

  • (A). BJT
  • (B). MOSFET
  • (C). GTO
  • (D). All of the above
    • View Answer

    Explanation: Not Avilable

    17. The load voltage of a chopper can be Controlled by varying the :

  • (A). Duty cycle
  • (B). Firing angle
  • (C). Reactor position
  • (D). Extinction angle
    • View Answer

    Explanation: Not Avilable

    18. In pule width modulation :

  • (A). The output voltage is modulated
  • (B). The input voltage is modulated
  • (C). The gating pulses are modulated
  • (D). None of the above
    • View Answer

    Explanation: Not Avilable

    19. The power MOSFET is a :

  • (A). Current controlled unipolar device
  • (B). Voltage controlled unipolar device
  • (C). Current control bipolar device
  • (D). Voltage controlled bipolar device
    • View Answer

    Explanation: Not Avilable

    20. A step down choppers can be used in :

  • (A). Electric traction
  • (B). Electric vehicle
  • (C). Machine tools
  • (D). All of these
    • View Answer

    Explanation: Not Avilable

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