Malvino Chapter 12 MCQ With Answers Electronics ECE Board Exam
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
b
2. The total ac emitter resistance of an emitter follower equals
a. re'
b. re
c. re + re'
d. RE
c
3. The input impedance of the base of an emitter follower is usually
a. Low
b. High
c. Shorted to ground
d. Open
b.
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
b
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
d
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
c
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
a
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
a
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
d
10. The output voltage of an emitter follower is approximately
a. 0
b. VG
c. vin
d. Vcc
c
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
c
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
d
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
d
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
b
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
c
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
c
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
d
18. A Darlington transistor has
a. A very low input impedance
b. Three transistors
c. A very high current gain
d. One VBE drop
c
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
b
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
a
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
a
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
d
23. Usually, the distortion in an emitter follower is
a. Very low
b. Very high
c. Large
d. Not acceptable
a
24. The distortion in an emitter follower is
a. Seldom low
b. Often high
c. Always low
d. High when clipping occurs
d
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
a
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
c
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
a
28. Thermal runaway is
a. Good for transistors
b. Always desirable
c. Useful at times
d. Usually destructive
d
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
b
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
c
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
b
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
d
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
d
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
c
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
d
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