Multiple Choice Questions and Answers on SCR

Multiple Choice Questions and Answers on SCR (Silicon Controlled Rectifiers)

 

Q1. An SCR has …………….. pn junctions

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

Answer : 2

Q2. An SCR is a solid state equivalent of …………….

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

Answer : 3

Q3. An SCR has ………….. semiconductor layers

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

Answer : 3

Q4. An SCR has three terminals viz ……………

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

Answer : 1

Q5. An SCR behaves as a ……………. switch

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

Answer : 1

Q6. An SCR is sometimes called …………

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

Answer : 4

Q7. An SCR is made of ………….

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

Answer : 2

Q8. 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

Answer : 3

Q9. 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

Answer : 1

Q10. 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

Answer : 2

Q11. The control element of an SCR is ………….

  1. Cathode
  2. Anode
  3. Anode supply
  4. Gate

Answer : 4

Q12. The normal way to turn on a SCR is by ……………..

  1. Breakover voltage
  2. Appropriate anode current
  3. Appropriate gate current
  4. None of the above

Answer : 3

Q13. 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

Answer : 1

Q14. An SCR is a ……………….. triggered device

  1. Voltage
  2. Current
  3. Voltage as well as current
  4. None of the above

Answer : 2

Q15. In an SCR circuit the supply voltage is generally ……….. that of breakover voltage

  1. Equal to
  2. Less than
  3. Greater than
  4. None of the above

Answer : 2

Q16. When an SCR is turned on, the voltage across it is about ……….

  1. Zero
  2. 10 V
  3. 1 V
  4. 1 V

Answer : 4

Q17. 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

Answer : 3

Q18. An SCR is turned off when …………..

  1. Anode current is reduced to zero
  2. Gate voltage is reduced to zero
  3. Gate is reverse biased
  4. None of the above

Answer : 1

Q19. In an SCR circuit, the angle of conduction can be changed by ……….

  1. Changing anode voltage
  2. Changing gate voltage
  3. Reverse biasing the gate
  4. None of the above

Answer : 2

Q20. 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

Answer : 3

Q21. 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

Answer : 1

Q22. 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

Answer : 2

Q23. 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

Answer : 4

Q24. We can control a.c. power in a load by connecting …………

  1. Two SCRs in series
  2. Two SCRs in parallel
  3. Two SCRs in parallel opposition
  4. None of the above

Answer : 3

Q25. When SCR starts conducting, then ……………. loses all control

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

Answer : 1

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