Power Electronics MCQs

1. The device which performs dc-dc conversion:

1. Inverter
2. Rectifier
3. Chopper
4. Switch

Correct answer: c. Chopper

Explanation: Chopper is an electrical device which converts dc to dc.

2. The DIAC is a:

1. One terminal device
2. Two terminal device
3. Three-terminal device
4. Four terminal device

Correct answer: b. Two terminal device

3. The TRIAC is:

1. An SCR
2. Made up of three DIAC’s
3. Is alike a bi-directional SCR
4. None of these

Correct answer: c. Is alike a bi-directional SCR

The structure of TRIAC matches two SCR’s which are joined back to back in a parallel fashion. Thus we can relate a TRIAC with a bi-directional SCR.

4. A thyristor has:

1. One pn junction
2. Two pn junctions
3. Three pn junctions
4. Four pn junctions

Correct answer: c. Three pn junctions

5. The SCS has:

1. Single gate terminal
2. Two gate terminals
3. Three gate terminals
4. Four gate terminals

Correct answer: b. Two gate terminals

6. Forced commutation on SCS can be achieved by:

1. Shorting anode and cathode terminals
2. By Applying a negative voltage between anode and cathode
3. Both of these
4. None of these

Correct answer: c. Both of these

7. The correct statement about SCR:

1. SCR is not a rectifier
2. A single SCR can’t be used in full ac control
3. SCR is not used commonly because it is very expensive
4. GTO is a variant of SCR

Correct answer: b. A single SCR can’t be used in full ac control

8. PUT stands for:

1. Programmable Unijunction Transistor
2. Positive Unijunction Transistor
3. Photoconductive Unijunction Transistor
4. Pi Unijunction Transistor

Correct answer: a. Programmable Unijunction Transistor

9. A DIAC conducts current in:

1. One direction
2. Two directions

Correct answer: b. Two directions

10. The LASCR is:

1. A laser activated SCR
2. A light-activated SCR
3. Lithium anode SCR
4. None of these

Correct answer: b. A light-activated SCR

11. Sort the correct statement about DIAC and TRIAC:

1. Both are bilateral devices
2. TRIAC is bilateral, but DIAC is unilateral
3. DIAC is bilateral, but TRIAC is unilateral
4. Both are unilateral devices

Correct answer: a. Both are bilateral devices

12. Which one the following is not a thyristor:

1. SCS
2. UJT
3. DIAC
4. TRIAC

Correct answer: b. UJT

13. The device which performs dc-ac conversion:

1. Inverter
2. Rectifier
3. Chopper
4. Switch

Correct answer: a. Inverter

14. The SCS is a _____ terminal thyristor that has _____ gate terminals.

1. Two, two
2. Two, four
3. Four, two
4. Four, one

Correct answer: c. Four, two

15. The SCS is turned on by:

1. Applying a negative pulse on anode gate
2. Applying a positive pulse on anode gate
3. Applying a negative pulse on cathode gate
4. None of these

Correct answer: a. Applying a negative pulse on anode gate

16. UJT has ______ pn junction/junctions:

1. Single
2. Two
3. Three
4. Four

Correct answer: 1. Single

17. Which one of the following is not a thyristor:

1. PUT
2. UJT
3. SCS
4. DIAC

Correct answer: b. UJT

18. LASCR is a:

1. Rectifier
2. Thyristor
3. Both of these
4. None of these

Correct answer: 3. Both of these

19. ______ has/have no gate terminal:

1. Diac
2. Triac
3. Both of these
4. None of these

Correct answer: a. Diac

20. The method which can be used to latch Shockley diode:

1. Exceed the critical rate of voltage rise from anode to cathode
2. Exceed the breakover voltage from anode to cathode
3. Both of these
4. None of these

Correct answer: 3. Both of these