19
3-8. What is the "tunneling phenomenon"
within the Zener diode?
1. An action where the minority carriers
tunnel across the junction to form the
current that occurs at breakdown
2. An action where the majority carriers
tunnel across the junction to form the
current that occurs at breakdown
3. An action that separates the
conduction band and the valence band
by a large gap
4. An action that removes all the
electrons from the conduction band
energy level
3-9. Which breakdown theory explains the
action that takes place in a heavily doped
PN junction with a reverse bias above 5
volts?
1. Zener effect
2. Avalanche breakdown
3. Energy band effect
4. Valence band gap crossing
3-10. Which breakdown theory explains the
action that takes place in a heavily doped
PN junction with a reverse bias below 5
volts?
1. Zener effect
2. Avalanche breakdown
3. Energy band effect
4. Valence band gap crossing
3-11. What happens to a Zener diode that has a
reverse bias slightly higher than the
breakdown voltage?
1. The Zener cuts off
2. The Zener acts like a short circuit
3. The Zener acts like an open circuit
4. The Zener conduction does not change
Figure 3A.—Schematic symbols.
IN ANSWERING QUESTIONS 3-12 AND 3-13,
REFER TO FIGURE 3-A.
3-12. Which of the symbols represents a Zener
diode?
1. A
2. B
3. C
4. D
3-13. In what direction does current flow in a
Zener diode?
1. From point 1 to point 2
2. From point 2 to point 1
3. From point 1 to point 2 to point 3
4. From point 3 to point 2 to point 1
3-14. Why is the Zener diode an ideal voltage
regulator?
1. It compensates for low supply voltage
2. It uses an unlimited number of carriers
3. Operating in the breakdown region
does not harm it
4. The voltage across the diode remains
almost constant after breakdown
