Boylestad: MCQ in PNPN and Other Devices

This is the Multiple Choice Questions in pnpn and Other Devices from the book Electronic Devices and Circuit Theory 10th Edition by Robert L. Boylestad. 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.

Online Questions and Answers Topic Outline

• MCQ in Introduction to pnpn and Other Devices | MCQ in Silicon-Controlled Rectifier (SCR) | MCQ in SCR Applications | MCQ in SCR Characteristics and Rating | MCQ in SCR Operation | MCQ in Silicon-Controlled Switch (SCS)| MCQ in Gate Turn-Off Switch (GTO) | MCQ in Light-Activated SCR (LASCR) | MCQ in Shockley Diode | MCQ in DIAC | MCQ in TRIAC | MCQ in Unijunction Transistor | MCQ in Phototransistors | MCQ in Opto-Isolators | MCQ in Programmable Unijunction Transistors (PUT)

Practice Exam Test Questions

Choose the letter of the best answer in each questions.

1. How many layers of semiconductor materials does a silicon-controlled rectifier (SCR) have?

A. 2

B. 3

C. 4

D. 5

2. Which of the following devices has (have) four layers of semiconductor materials?

A. Silicon-controlled switch (SCS)

B. Gate turn-off switch (GTO)

C. Light-activated silicon-controlled rectifier (LASCR)

D. All of the above

3. A thyristor is a _____-layer semiconductor material device.

A. 2

B. 3

C. 4

D. 5

4. Which of the following devices is unquestionably of the greatest interest today?

A. SCR

B. GTO

C. LASCR

D. SCS

5. What is the frequency range of application of SCRs?

A. About 10 kHz

B. About 50 kHz

C. About 250 kHz

D. About 1 mHz

6. Which one of the SCR terminals fires the SCR?

A. Anode

B. Cathode

C. Gate

D. All of the above

7. What is the typical value of the reverse resistance of SCRs?

A. 1 Ω to 10 Ω

B. 100 Ω to 1 kΩ

C. 1 k Ω to 50 kΩ

D. 100 kΩ or more

8. Which of the following transistors is an SCR composed of?

A. npn, pnp

B. npn, npn

C. pnp, pnp

D. None of the above

9. Which of the transistors of an SCR are conducting when the SCR is fired and is in the conduction mode?

A. npn

B. pnp

C. Both npn and pnp

D. Neither npn nor pnp

10. What is the range of the turn-on times in high-power SCR devices?

A. 30 µs to 100 µs

B. 10 µs to 25 µs

C. 5 µs to 8 µs

D. 1 µs to 5 µs

11. What is the typical range of turn-off times for SCRs?

A. 5 µs to 30 µs

B. 1 µs to 5 µs

C. 0.1 µs to 1 µs

D. 0.01 µs to 0.1 µs

12. This symbol is an example of a(n) ______.

A. SCR

B. SCS

C. GTO

D. DIAC

13. Which of the following parameters are usually provided by the manufacturer on the specification sheet for SCRs?

A. Turn-on time (ton )

B. Turn-off time (toff )

C. Junction and case temperatures (tj and tc )

D. All of the above

14. How many terminals does a silicon-controlled switch (SCS) device have?

A. 2

B. 3

C. 4

D. 5

15. What is the typical value of the triggering anode gate for SCS devices?

A. 1.5 mA

B. 150 A

C. 15 A

D. 1 A

16. Which of the following is (are) the advantages of the SCS over a corresponding SCR?

A. Reduced turn-off time

B. Increased control and triggering sensitivity

C. More predictable firing situation

D. All of the above

17. Which of the following areas is (are) applications of an SCS?

A. Counters

B. Pulse generators

C. Voltage sensors

D. All of the above

18. This symbol is an example of a(n)______.

A. SCR

B. SCS

C. GTO

D. DIAC

19. For an SCS, a ______ pulse at the anode gate turns the device on, while a ______ pulse will turn it off.

A. negative, positive

B. positive, negative

20. An advantage of the SCR over the SCS is the reduced turn-off time.

A. True

B. False

21. Which of the following devices has the smallest turn-off time?

A. SCR

B. GTO

C. SCS

D. LASCR

22. Which of the following devices has nearly the same turn-on time as turn-off time?

A. SCR

B. GTO

C. SCS

D. LASCR

23. This symbol is an example of a(n) _____.

A. SCR

B. SCS

C. GTO

D. diac

24. What is the maximum current (rms) rating for commercially available LASCRs today?

A. 3 A

B. 15 A

C. 20 A

D. 25 A

25. How many terminals does a Shockley diode have?

A. 5

B. 4

C. 3

D. 2

26. This symbol is an example of a(n) _____.

A. SCR

B. SCS

C. GTO

D. DIAC

27. Which of the following devices does not have a cathode terminal?

A. SCR

B. SCS

C. Triac

D. Shockley diode

28. Today, the SCR is more widely used than the TRIAC.

A. True

B. False

29. Which of the following devices has a negative-resistance region in its characteristics curve?

A. SCR

B. SCS

C. Unijunction transistor

D. Phototransistor

30. What is the range of the variable resistor in the equivalent circuit of a unijunction transistor?

A. 50 Ω to 5 kΩ

B. 6 kΩ to 10 kΩ

C. 5 Ω to 50 Ω

D. 1 Ω to 5 Ω

31. This is an example of a high-isolation _____ gate.

A. OR

B. NOT

C. AND

D. NAND

32. The ISO-LIT Q1 16-pin Litronix opto-isolator DIP contains _____ opto-isolators.

A. 4

B. 8

C. 12

D. 6

33. How many terminals does a programmable unijunction transistor (PUT) have?

A. 4

B. 3

C. 2

D. 1

34. Determine RB1 for a silicon PUT if it is determined that h = 0.84, VP = 11.2 V, and RB2 = 5 kΩ.

A. 12.65 kΩ

B. 16.25 kΩ

C. 20.00 kΩ

D. 26.25 kΩ

FILL-IN-THE-BLANKS

1. The two-layer semiconductor diode has led to ______ layer devices.

A. three-

B. four-

C. five-

D. All of the above

2. The four-layer devices with a control mechanism are commonly referred to as ______.

A. thyristors

B. transistors

C. diodes

D. None of the above

3. ______ are areas of application for SCRs.

A. Relay controls

B. Time-delay circuits

C. Motor controls

D. All of the above

4. SCRs have been designed to control powers as high as _____, with individual ratings as high as _____ at _____.

A. 1800 MW, 10 A, 2000 V

B. 1800 MW, 2000 A, 10 V

C. 10 MW, 2000 A, 1800 V

D. 2000 MW, 10 A, 1800 V

5. The _____ are the terminals of SCRs.

A. anode and cathode

B. anode, gate, and cathode

C. base, anode, and cathode

D. gate and anode

6. In the conduction region, the dynamic resistance of the SCR is typically _____ to _____.

A. 0.01 Ω, 0.1 Ω

B. 1 Ω, 10 Ω

C. 50 Ω, 100 Ω

D. 500 Ω, 10 kΩ

7. The SCRs have typical turn-on times of _____ in the regeneration action.

A. 0.1 μs to 1 μs

B. 0.1 ms to 1 ms

C. 3 ms to 5 ms

D. 5 ms to 9 ms

8. The method(s) for turning off an SCR is (are) categorized as ______.

A. current interruption

B. forced commutation

C. both current interruption and forced commutation

D. None of the above

9. At –65ºC the minimum current that will trigger the series of an SCR is _____, while at +150ºC only _____ is required.

A. 20 mA, 100 mA

B. 50 mA, 75 mA

C. 75 mA, 50 mA

D. 100 mA, 20 mA

10. In a half-wave variable-resistance phase control operation, the control cannot be extended past a ______ phase displacement.

A. 45°

B. 90°

C. 135°

D. 180°

11. The _____ are the terminals of an SCS.

A. anode, anode gate, cathode gate, and cathode

B. anode, cathode, cathode gate, and gate

C. anode, anode gate, cathode, and gate

D. anode, cathode, and gate

12. The _____ the anode gate current, the _____ the required anode-to-cathode voltage to turn the SCS device on.

A. higher, higher

B. lower, lower

C. higher, lower

D. None of the above

13. The anode gate connection can be used to turn the SCS device _____.

A. on

B. off

C. neither on nor off

D. either on or off

14. To turn on an SCS device, a _____ pulse must be applied to the anode gate terminal; to turn off the device, a _____ pulse is required.

A. positive, positive

B. negative, positive

C. positive, negative

D. negative, negative

15. In general, the triggering (turn-on) anode gate current is _____ the required cathode gate current.

A. larger than

B. the same as

C. smaller than

D. None of the above

16. A(n) _____ can be triggered in either direction.

A. SCR

B. Shockley diode

C. diac

D. SCS

17. _____ is (are) the element(s) of a unijunction transistor’s equivalent circuit.

A. One fixed resistor

B. A variable resistor

C. A diode

D. All of the above

18. The current induced by photoelectric effects is the _____ current of the transistor.

A. collector

B. base

C. emitter

D. None of the above

19. _____ in light intensity corresponds with _____ in collector current.

A. An increase, an increase

B. An increase, a decrease

C. A decrease, an increase

D. None of the above

20. _____ is(are) example(s) of applications of phototransistors.

A. Punch-card readers

B. Lighting control (for example, on highways)

C. Level indication

D. All of the above

21. An opto-isolator contains _____.

A. an infrared LED

B. a photodetector

C. both an infrared LED and a photodetector

D. None of the above

22. The switching time of an opto-isolator _____ with increased current, while for many devices it is exactly the reverse.

A. increases

B. decreases

C. remains the same

D. None of the above

23. In a programmable unijunction transistor (PUT), the ______ can be controlled through a couple of resistors and the supply voltage.

A. interbase resistance RBB

B. intrinsic stand-off ratio

C. emitter firing potential VP

D. All of the above

24. The peak and valley currents of the PUT are typically ______ those of a similarly rated UJT.

A. lower than

B. the same as

C. higher than

D. None of the above

25. The minimum operating voltage of the UJT is typically ______ that of a similarly rated PUT.

A. lower than

B. the same as

C. higher than

D. None of the above

Check your work.

Complete List of Chapter Quiz in Electronic Devices and Circuit Theory