Malvino Chapter 15

Chapter 15 

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 overvoltages 
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 




Also try:

Malvino Chapter 1
Malvino Chapter 2
Malvino Chapter 3
Malvino Chapter 4
Malvino Chapter 5
Malvino Chapter 6
Malvino Chapter 7
Malvino Chapter 8
Malvino Chapter 9
Malvino Chapter 10
Malvino Chapter 11
Malvino Chapter 12
Malvino Chapter 13
Malvino Chapter 14
Malvino Chapter 16
Malvino Chapter 17
Malvino Chapter 18
Malvino Chapter 19
Malvino Chapter 20
Malvino Chapter 21
Malvino Chapter 22
Malvino Chapter 23
Malvino Chapter 24