Malvino Chapter 15 MCQ With Answers Electronics ECE Board Exam

Malvino Chapter 15 MCQ With Answers Electronics ECE Board Exam




1. A thyristor can be used as

a. A resistor
b. An amplifier
c. A switch
d. A power source
c. A switch
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
b. Aids the original change

3. A latch always uses

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

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
b. Trigger current

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
b. Low-current drop out

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
a. Holding current
8. A silicon controlled rectifier has
a. Two external leads
b. Three external leads
c. Four external leads
d. Three doped regions
b. Three external leads

9. A SCR is usually turned on by

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




10. SCRs are

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

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
a. Crowbar

12. An RC snubber protects an SCR against

a. Supply overvoltages
b. False triggering
c. Breakover
d. Crowbarring
b. False triggering

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
d. Current limiting
14.  The photo-SCR responds to

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

15. The diac is a
a. Transistor
b. Unidirectional device
c. Three-layer device
d. Bidirectional device
d.  Light

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
d

17. The unijunction transistor acts as a

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





18. Any thyristor can be turned on with

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

19. A Shockley diode is the same as a

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

20. The trigger voltage of an SCR is closest to

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

21. Any thyristor can be turned off with

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

22. Exceeding the critical rate of rise produces

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

23. A four-layer diode is sometimes called a

a. Unijunction transistor
b. Diac
c. pnpn diode
d. Switch
c

24. A latch is based on

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

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