Topic Outline
- MCQs in Amplifier Terms
- MCQs in Two Load Lines
- MCQs in Class A Operation
- MCQs in Class B Operation
- MCQs in Class B Push-Pull Emitter Follower
- MCQs in Biasing Class B and Class AB Amplifiers
- MCQs in Class B and Class AB Drivers
- MCQs in Class C Operation
- MCQs in Class C Formulas
- MCQs in Transistor Power Rating
Start Practice Exam Test Questions
Choose the letter of the best answer in each questions.
1. An emitter follower has a voltage gain that is
- a. Much less than one
- b. Approximately equal to one
- c. Greater than one
- d. Zero
2. The total ac emitter resistance of an emitter follower equals
- a. re'
- b. re
- c. re + re'
- d. RE
3. The input impedance of the base of an emitter follower is usually
- a. Low
- b. High
- c. Shorted to ground
- d. Open
4. The dc emitter current for class A emitter followers is
- a. The same as the ac emitter current
- b. VE divided by RE
- c. Vc divided by Rc
- d. The same as the load current
5. The ac base voltage of an emitter follower is across the
- a. Emitter diode
- b. DC emitter resistor
- c. Load resistor
- d. Emitter diode and external ac emitter resistance
6. The output voltage of an emitter follower is across the
- a. Emitter diode
- b. DC collector resistor
- c. Load resistor
- d. Emitter diode and external ac emitter resistance
7. If Beta = 200 and re = 150 ohm, the input impedance of the base is approximately
- a. 30 kohm
- b. 600 n
- c. 3 kohm
- d. 5 kohm
8. The input voltage to an emitter follower is usually
- a. Less than the generator voltage
- b. Equal to the generator voltage
- c. Greater than the generator voltage
- d. Equal to the supply voltage
9. The ac emitter current is closest to
- a. VG divided by re
- b. Vin divided by re'
- c. VG divided by re'
- d. Vin divided by re
10. The output voltage of an emitter follower is approximately
- a. 0
- b. VG
- c. Vin
- d. Vcc
11. The ac load line of an emitter follower is usually
- a. The same as the dc load line
- b. More horizontal than the dc load line
- c. Steeper than the dc load line
- d. Vertical
12. If the input voltage to an emitter follower is too large, the output voltage will be
- a. Smaller
- b. Larger
- c. Equal
- d. Clipped
13. If the Q point is at the middle of the dc load line, clipping will first occur on the
- a. Left voltage swing
- b. Upward current swing
- c. Positive half cycle of input
- d. Negative half cycle of input
14. If an emitter follower has VCEQ = 5 V, ICQ = 1 mA, and re = 1 kohm, the maximum peak-to-peak unclipped output is
- a. 1 V
- b. 2 V
- c. 5 V
- d. 10 V
15. If the load resistance of an emitter follower is very large, the external ac emitter resistance equals
- a. Generator resistance
- b. Impedance of the base
- c. DC emitter resistance
- d. DC collector resistance
16. If an emitter follower has re' = 10 ohm and re = 90 ohm, the voltage gain is approximately
- a. 0
- b. 0.5
- c. 0.9
- d. 1
17. A square wave out of an emitter follower implies
- a. No clipping
- b. Clipping at saturation
- c. Clipping at cutoff
- d. Clipping on both peaks
18. A Darlington transistor has
- a. A very low input impedance
- b. Three transistors
- c. A very high current gain
- d. One VBE drop
19. The ac load line of the emitter follower is
- a. The same as the dc load line
- b. Different from the dc load line
- c. Horizontal
- d. Vertical
20. If the generator voltage is 5 mV in an emitter follower, the output voltage across the load is closest to
- a. 5 mV
- b. 150 mV
- c. 0.25 V
- d. 0.5 V
21. If the load resistor of Fig. 12-la in your textbook is shorted, which of the following are different from their normal values:
- a. Only ac voltages
- b. Only dc voltages
- c. Both dc and ac voltages
- d. Neither dc nor ac voltages
22. If R1 is open in an emitter follower, which of these is true?
- a. DC base voltage is Vcc
- b. DC collector voltage is zero
- c. Output voltage is normal
- d. DC base voltage is zero
23. Usually, the distortion in an emitter follower is
- a. Very low
- b. Very high
- c. Large
- d. Not acceptable
24. The distortion in an emitter follower is
- a. Seldom low
- b. Often high
- c. Always low
- d. High when clipping occurs
25. If a CE stage is direct coupled to an emitter follower, how many coupling capacitors are there between the two stages?
- a. 0
- b. 1
- c. 2
- d. 3
26. A Darlington transistor has a Beta of 8000. If RE = 1 kohm and RL = 100 ohm, the input impedance of the base is closest to
- a. 8 kohm
- b. 80 kohm
- c. 800 kohm
- d. 8 Mohm
27. The transistors of a class B push-pull emitter follower are biased at or near
- a. Cutoff
- b. The center of the dc load line
- c. Saturation
- d. The center of the ac load line
28. Thermal runaway is
- a. Good for transistors
- b. Always desirable
- c. Useful at times
- d. Usually destructive
29. The ac resistance of compensating diodes
- a. Must be included
- b. Is usually small enough to ignore
- c. Compensates for temperature changes
- d. Is very high
30. A small quiescent current is necessary with a class B push-pull amplifier to avoid
- a. Thermal runaway
- b. Destroying the compensating diodes
- c. Crossover distortion
- d. Excessive current drain
31. The zener current in a zener follower is
- a. Equal to the output current
- b. Smaller than the output current
- c. Larger than the output current
- d. Prone to thermal runaway
32. In the two-transistor voltage regulator, the output voltage
- a. Is regulated
- b. Has much smaller ripple than the input voltage
- c. Is larger than the zener voltage
- d. All of the above
33. For a class B push-pull emitter follower to work properly, the emitter diodes must
- a. Be able to control the quiescent current
- b. Have a power rating greater than the output power
- c. Have a voltage gain of I
- d. Match the compensating diodes
34. The maximum efficiency of a class B push-pull amplifier is
- a. 25 percent
- b. 50 percent
- c. 78.5 percent
- d. 100 percent
35. The ac emitter resistance of an emitter follower
- a. Equals the dc emitter resistance
- b. Is larger than the load resistance
- c. Has no effect on MPP
- d. Is usually less than the load resistance
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