_______________________________________________________________________ Special Devices
CHAPTER 3
CHECK-ON-LEARNING QUESTIONS
When you are satisfied that you have answered every question to the best of your ability,
check your answers using Appendix A. If you missed eight or more questions, you should
review the chapter, paying particular attention to the areas in which your answers were
incorrect.
In a reverse-biased PN junction, the presence of what causes a small leakage current?
1.
The action of a PN junction during breakdown can be explained by what two theories?
2.
Which breakdown theory explains the action that takes place in a heavily doped PN
3.
junction with a reverse bias of less than 5 volts?
What is the name of the gap (where electrons must cross) between the valence band energy
4.
level and the conduction band energy level?
During Avalanche effect breakdown, what limits current flow through the diode?
5.
For what are Zener diodes mostly used?
6.
What is the name of the theory where an electron crosses a junction without having
7.
sufficient energy?
What is the net current flow when current carriers move across the depletion region due to
8.
thermal energy?
What is the most important and widely used characteristic of the tunnel diode?
9.
What is the name of the region that is void of positive and negative charged current carriers
10.
surrounding the P and N materials?
To what is the size of the depletion region in a varactor diode related?
11.
When a PN junction is forward biased, what happens to the depletion region?
12.
What is one advantage of the varactor?
13.
What is the basic purpose of the SCR?
14.
The SCR is made up of how many layers of semiconductor material?
15.
The SCR turns off automatically when what power source is used?
16.
The triac is similar in operation to what device?
17.
When used for AC current control, during which alternation of the AC cycle does the triac
18.
control current flow?
What type of bias is required to cause an LED to produce light?
19.
What is the LED operating voltage when forward bias?
20.
What type voltage do you apply to the seven-segment display to form numbers?
21.
What is the resistance level of a photodiode in total darkness?
22.
What type of bias is required for proper operation of a photodiode?
23.
What is a typical light-to-dark resistance ratio for a photocell?
24.
What device converts light energy into electrical energy?
25.
23 June 2005
TC 9-62
3-41
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