PNPN Questions and Answers
The PNPN structure forms the basis of semiconductor devices like SCRs and thyristors, making it a key topic in electronics aptitude exams. Questions related to PNPN are often included in aptitude questions and answers sections for GATE, ISRO, and PSU recruitment tests. Understanding its layer structure, operation, and switching characteristics helps you analyze semiconductor behavior effectively. This guide presents PNPN questions with answers and explanations designed for quick learning. Practicing these aptitude test practice online questions will strengthen your core knowledge in power electronics and improve your performance in technical exams.
PNPN
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24 questions
11. Which of the following devices has nearly the same turn-on time as turn-off time?
- SCR
- GTO
- SCS
- LASCR
12. Which of the transistors of an SCR are conducting when the SCR is fired and is in the conduction mode?
- npn
- pnp
- Both npn and pnp
- Neither npn nor pnp
13. For an SCS, a ________ pulse at the anode gate turns the device on, while a ________ pulse will turn it off.
- negative, positive
- positive, negative
14. An advantage of the SCR over the SCS is the reduced turn-off time.
- TRUE
- FALSE
15. Which of the following devices has (have) four layers of semiconductor materials?
- Silicon-controlled switch (SCS)
- Gate turn-off switch (GTO)
- Light-activated silicon-controlled rectifier (LASCR)
- All of the above
16. Which of the following parameters are usually provided by the manufacturer on the specification sheet for SCRs?
- Turn-on time (ton )
- Turn-off time (toff )
- Junction and case temperatures (tj and tc )
- All of the above
17. What is the maximum current (rms) rating for commercially available LASCRs today?
- 3 A
- 15 A
- 20 A
- 25 A
18. Which of the following areas is (are) applications of an SCS?
- Counters
- Pulse generators
- Voltage sensors
- All of the above
19. How many terminals does a silicon-controlled switch (SCS) device have?
- 2
- 3
- 4
- 5
20. What is the typical value of the triggering anode gate for SCS devices?
- 1.5 mA
- 150 A
- 15 A
- 1 A