Silicon Controlled Rectifier - SCR Multiple Choice Questions and Answers for Practice

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

1. Exactly zero
2. Small leakage current
3. Large leakage current
4. None of the above

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

1. Gate
2. Cathode
3. Anode
4. None of the above

18. An SCR is made of ………….

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

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

1. Is decreased
2. Is increased
3. Remains the same
4. None of the above

20. If gate current is increased, then anode-cathode voltage at which SCR turns ON

1. is decreased
2. is increased
3. remains the same
4. none of the above

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

1. Is inexpensive
2. Is mechanically strong
3. Has small leakage current
4. Is tetravalent

22. 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

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

1. Positive half-cycles only
2. Negative half-cycles only
3. Both positive and negative half-cycles
4. Positive or negative half-cycles

24. In AC supply, an SCR can exercise control over

1. Positive half-cycles only
2. Negative half-cycles only
3. Both positive and negative half-cycles
4. Positive or negative half-cycles

25. A single phase ac - dc converter is also known as

1. rectifier
2. inverter
3. chopper
4. regulator

26. An SCR is turned off by …………….

1. Reducing anode voltage to zero
2. Reducing gate voltage to zero
3. Reverse biasing the gate
4. None of the above

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

1. Remains the same
2. Is increased
3. Is decreased
4. None of the above

28. If firing angle is increased, then the output of an SCR

1. Remains the same
2. Is increased
3. Is decreased
4. None of the above

29. An SCR is sometimes called …………

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

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

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