Thyristors Questions and Answers

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Thyristors are semiconductor devices widely used for controlling high-power electrical applications such as rectifiers, converters, and AC regulators. Understanding thyristor operation and characteristics is vital for candidates appearing in GATE, DRDO, and JE-level electrical exams. Our set of Thyristors questions with answers provides detailed aptitude questions and answers to help you master triggering methods, turn-off techniques, and VI characteristics. Designed for aptitude test practice online, this content enables students to strengthen their conceptual clarity and score high in technical competitive exams and interviews.

Thyristors

Showing 10 of 24 questions

11. Which of the following devices might best be used to control an electric motor?

  • an SCS
  • a PUT
  • an SCR
  • a diac
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12. You have a light-dimmer circuit using an SCR. In testing the circuit, you find that IG = 0 mA and the light is still on. You conclude that the trouble might be one of the following:

  • the SCR is open.
  • the switch is faulty.
  • the gate circuit is shorted.
  • this is normal; nothing is wrong.
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13. How many semiconductor layers are thyristors constructed with?

  • 2
  • 3
  • 4
  • 5
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14. Your boss has asked you to recommend a thyristor that will enable you to turn it on with a pulse and also turn it off with a pulse. Which of the following should you recommend?

  • an SCR
  • an SCS
  • a PUT
  • a triac
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15. An SCR acts to control the speed of an electric motor by ________ the ________ of the pulse delivered to the motor.

  • varying, width
  • increasing, amplitude
  • decreasing, gate width
  • none of these
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16. The anode-to-gate voltage can be used to turn the PUT on or off.

  • TRUE
  • FALSE
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17. In an SCR-based half-wave phase-control circuit, a diode is connected in series with the anode.

  • TRUE
  • FALSE
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18. The SCS is turned on with the cathode gate, and turned off with the anode gate.

  • TRUE
  • FALSE
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19. UJTs can only be used to trigger triacs, not SCRs.

  • TRUE
  • FALSE
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20. The SCR is a device that can be triggered off by a pulse applied to the gate.

  • TRUE
  • FALSE
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