50 TOP SCR SILICON CONTROLLED RECTIFIERS Questions and Answers pdf | MCQs

SILICON CONTROLLED RECTIFIERS Questions and Answers pdf :-

1. An SCR has …………….. pn junctions

  1. Two
  2. Three
  3. Four
  4. None of the above
    ANS : 2

2. An SCR is a solid state equivalent of …………….

  1. Triode
  2. Pentode
  3. Gas-filled triode
  4. Tetrode
    ANS : 3

3. An SCR has ………….. semiconductor layers

  1. Two
  2. Three
  3. Four
  4. None of the above
    ANS : 3
SILICON CONTROLLED RECTIFIERS Questions and Answers pdf
SILICON CONTROLLED RECTIFIERS Questions

4. An SCR has three terminals viz ……………

  1. Cathode, anode, gate
  2. Anode, cathode, grid
  3. Anode, cathode, drain
  4. None of the above
    ANS : 1

5. An SCR behaves as a ……………. switch

  1. Unidirectional
  2. Bidirectional
  3. Mechanical
  4. None of the above
    ANS : 1

6. An SCR is sometimes called …………

  1. Triac
  2. Diac
  3. Unijunction transistor
  4. Thyristor
    ANS : 4

7. An SCR is made of ………….

  1. Germanium
  2. Silicon
  3. Carbon
  4. None of the above
    ANS : 2

8. In the normal operation of an SCR, anode is …………… w.r.t. cathode

  1. At zero potential
  2. Negative
  3. Positive
  4. None of the above
    ANS : 3

9. In normal operation of an SCR, gate is ………..w.r.t. cathode

  1. Positive
  2. Negative
  3. At zero potential
  4. None of the above
    ANS : 1

10. An SCR combines the features of …………..

  1. A rectifier and resistance
  2. A rectifier and transistor
  3. A rectifier and capacitor
  4. None of the above
    ANS : 2

11. The control element of an SCR is ………….

Cathode
Anode
Anode supply
Gate
ANS : 4

12. The normal way to turn on a SCR is by ……………..

Breakover voltage
Appropriate anode current
Appropriate gate current
None of the above
ANS : 3

13. An SCR is turned off by …………….

Reducing anode voltage to zero
Reducing gate voltage to zero
Reverse biasing the gate
None of the above
ANS : 1

14. An SCR is a ……………….. triggered device

Voltage
Current
Voltage as well as current
None of the above
ANS : 2

15. In an SCR circuit the supply voltage is generally ……….. that of breakover voltage

Equal to
Less than
Greater than
None of the above
ANS : 2

16. When an SCR is turned on, the voltage across it is about ……….

Zero
10 V
1 V
1 V
ANS : 4

17. An SCR is made of silicon and not germanium because silicon ………

Is inexpensive
Is mechanically strong
Has small leakage current
Is tetravalent
ANS : 3

18. An SCR is turned off when …………..

Anode current is reduced to zero
Gate voltage is reduced to zero
Gate is reverse biased
None of the above
ANS : 1

19. In an SCR circuit, the angle of conduction can be changed by ……….

Changing anode voltage
Changing gate voltage
Reverse biasing the gate
None of the above
ANS : 2

20. If firing angle in an SCR circuit is increased, the output …………

Remains the same
Is increased
Is decreased
None of the above
ANS : 3

21. If gate current is increased, then anode-cathode voltage at which SCR closes …………….

Is decreased
Is increased
Remains the same
None of the above
ANS : 1

22. When SCR is OFF, the current in the circuit is …………….

Exactly zero
Small leakage current
Large leakage current
None of the above
ANS : 2

23. An SCR can exercise control over ………. of a.c. supply

Positive half-cycles only
Negative half-cycles only
Both positive and negative half-cycles
Positive or negative half-cycles
ANS : 4

24. We can control a.c. power in a load by connecting …………

Two SCRs in series
Two SCRs in parallel
Two SCRs in parallel opposition
None of the above
ANS : 3

25. When SCR starts conducting, then ……………. loses all control

Gate
Cathode
Anode
None of the above
ANS : 1

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