Malvino: MCQ in Thyristors

(Last Updated On: February 7, 2020)

This is the Multiple Choice Questions in Chapter 15: Thyristors from the book Electronic Principles 7th Edition by Albert Malvino. If you are looking for a reviewer in Electronics Engineering this will definitely help. I can assure you that this will be a great help in reviewing the book in preparation for your Board Exam. Make sure to familiarize each and every questions to increase the chance of passing the ECE Board Exam.

Topic Outline

• MCQs in Four-Layer Diode
• MCQs in Silicon Controlled Rectifier (SCR)
• MCQs in SCR Crowbar
• MCQs in SCR Phase Control
• MCQs in Bidirectional Thyristor
• MCQs in IGBTs
• MCQs in Other Thyristors

Start Practice Exam Test Questions

Choose the letter of the best answer in each questions.

1. A thyristor can be used as

• a. A resistor
• b. An amplifier
• c. A switch
• d. A power source

2. Positive feedback means the returning signal

• a. Opposes the original change
• b. Aids the original change
• c. Is equivalent to negative feedback
• d. Is amplified

3. A latch always uses

• a. Transistors
• b. Feedback
• c. Current
• d. Positive feedback

4. To turn on a four-layer diode, you need

• a. A positive trigger
• b. low-current drop out
• c. Breakover
• d. Reverse-bias triggering

5. The minimum input current that can turn on a thyristor is called the

• a. Holding current
• b. Trigger current
• c. Breakover current
• d. Low-current drop out

6. The only way to stop a four-layer diode that is conducting is by

• a. A positive trigger
• b. Low-current drop out
• c. Breakover
• d. Reverse-bias triggering

7. The minimum anode current that keeps a thyristor turned on is called the

• a. Holding current
• b. Trigger current
• c. Breakover current
• d. Low-current drop out

8. A silicon controlled rectifier has

• a. Two external leads
• b. Three external leads
• c. Four external leads
• d. Three doped regions

9. A SCR is usually turned on by

• a. Breakover
• b. A gate trigger
• c. Breakdown
• d. Holding current

10. SCRs are

• a. Low-power devices
• b. Four-layer diodes
• c. High-current devices
• d. Bidirectional

11. The usual way to protect a load from excessive supply voltage is with a

• a. Crowbar
• b. Zener diode
• c. Four-layer diode
• d. Thyristor

12. An RC snubber protects an SCR against

• a. Supply over voltages
• b. False triggering
• c. Breakover
• d. Crowbarring

13. When a crowbar is used with a power supply, the supply needs to have a fuse or

• a. Adequate trigger current
• b. Holding current
• c. Filtering
• d. Current limiting

14. The photo-SCR responds to

• a. Current
• b. Voltage
• c. Humidity
• d. Light

15. The diac is a

• a. Transistor
• b. Unidirectional device
• c. Three-layer device
• d. Bidirectional device

16. The triac is equivalent to

• a. A four-layer diode
• b. Two diacs in parallel
• c. A thyristor with a gate lead
• d. Two SCRs in parallel

17. The unijunction transistor acts as a

• a. Four-layer diode
• b. Diac
• c. Triac
• d. Latch

18. Any thyristor can be turned on with

• a. Breakover
• b. Forward-bias triggering
• c. Low-current dropout
• d. Reverse-bias triggering

19. A Shockley diode is the same as a

• a. four-layer diode
• b. SCR
• c. diac
• d. triac

20. The trigger voltage of an SCR is closest to

• a. 0
• b. 0.7 V
• c. 4 V
• d. Breakover voltage

21. Any thyristor can be turned off with

• a. Breakover
• b. Forward-bias triggering
• c. Low-current drop out
• d. Reverse-bias triggering

22. Exceeding the critical rate of rise produces

• a. Excessive power dissipation
• b. False triggering
• c. Low-current drop out
• d. Reverse-bias triggering

23. A four-layer diode is sometimes called a

• a. Unijunction transistor
• b. Diac
• c. PNPN diode
• d. Switch

24. A latch is based on

• a. Negative feedback
• b. Positive feedback
• c. The four-layer diode
• d. SCR action

Check your work.

Complete List of MCQ in Electronic Principles by Albert Malvino