Electronic Devices-Thyristors

Electronic Devices-Thyristors
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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Electrical Engineering
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