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scr silicon controlled rectifiers MCQs

Practise focused scr silicon controlled rectifiers questions with marked answers for exam preparation and subject revision.

scr silicon controlled rectifiers Mcqs

1. We can control a.c. power in a load by connecting ______________?
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A. Two SCRs in parallel

B. None of the above

C. Two SCRs in parallel opposition

D. Two SCRs in series

2. An SCR can exercise control over____________of a.c. supply?
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A. Positive half-cycles only

B. Negative half-cycles only

C. Both positive and negative half-cycles

D. Positive or negative half-cycles

3. An SCR combines the features of ____________?
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A. A rectifier and resistance

B. None of the above

C. A rectifier and capacitor

D. A rectifier and transistor

4. An SCR behaves as a____________switch?
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A. Bidirectional

B. Mechanical

C. Unidirectional

D. None of the above

5. An SCR has __________ pn junctions?
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A. Two

B. Four

C. None of the above

D. Three

6. An SCR is sometimes called ____________?
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A. Diac

B. Triac

C. Unijunction transistor

D. Thyristor

7. An SCR is turned off by _________________?
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A. None of the above

B. Reverse biasing the gate

C. Reducing gate voltage to zero

D. Reducing anode voltage to zero

8. An SCR is a solid state equivalent of ______________?
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A. Tetrode

B. Triode

C. Gas-filled triode

D. Pentode

9. An SCR is a ____________ triggered device?
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A. Voltage

B. None of the above

C. Current

D. Voltage as well as current

10. An SCR has three terminals viz ________________?
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A. Anode, cathode, grid

B. Cathode, anode, gate

C. None of the above

D. Anode, cathode, drain

11. When an SCR is turned on, the voltage across it is about _____________?
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A. 1 V

B. 1 V

C. 10 V

D. Zero

12. An SCR has ___________semiconductor layers?
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A. None of the above

B. Three

C. Two

D. Four

13. When SCR starts conducting, then _____________ loses all control?
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A. Anode

B. None of the above

C. Gate

D. Cathode

14. If firing angle in an SCR circuit is increased, the output _____________?
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A. None of the above

B. Remains the same

C. Is decreased

D. Is increased

15. In normal operation of an SCR, gate is _____________w.r.t. cathode?
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A. None of the above

B. At zero potential

C. Negative

D. Positive

16. When SCR is OFF, the current in the circuit is ________________?
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A. None of the above

B. Exactly zero

C. Small leakage current

D. Large leakage current

17. In an SCR circuit the supply voltage is generally ___________ that of breakover voltage?
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A. Equal to

B. Greater than

C. None of the above

D. Less than

18. The control element of an SCR is ______________?
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A. Anode

B. Anode supply

C. Gate

D. Cathode

19. In an SCR circuit, the angle of conduction can be changed by__________________?
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A. None of the above

B. Changing gate voltage

C. Reverse biasing the gate

D. Changing anode voltage

20. An SCR is made of_______________?
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A. Germanium

B. None of the above

C. Carbon

D. Silicon

21. An SCR is turned off when ________________?
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A. Gate voltage is reduced to zero

B. None of the above

C. Anode current is reduced to zero

D. Gate is reverse biased

22. The normal way to turn on a SCR is by______________?
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A. Breakover voltage

B. None of the above

C. Appropriate gate current

D. Appropriate anode current

23. If gate current is increased, then anode-cathode voltage at which SCR closes_________________?
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A. Is increased

B. None of the above

C. Remains the same

D. Is decreased

24. An SCR is made of silicon and not germanium because silicon _________________?
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A. Is mechanically strong

B. Has small leakage current

C. Is tetravalent

D. Is inexpensive

25. In the normal operation of an SCR, anode is __________ w.r.t. cathode?
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A. Positive

B. Negative

C. At zero potential

D. None of the above

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