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transistor audio power amplifiers MCQs

Practise focused transistor audio power amplifiers questions with marked answers for exam preparation and subject revision.

transistor audio power amplifiers Mcqs
1. Class_____________ power amplifier has the highest collector efficiency ?
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A. A

B. B

C. AB

D. C
2. The most costly coupling is _______________ coupling?
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A. Impedance

B. Direct

C. RC

D. Transformer
3. Power amplifiers handle ______________ signals compare to voltage amplifiers?
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A. Small

B. Very small

C. Large

D. None of the above

4. The output signal voltage and current of a power amplifier are 5V and 200 mA; the values being r.m.s. What is the power output ?
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A. 1 W

B. None of the above

C. 2 W

D. 4 W

5. A power amplifier has comparatively __________________ ?
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A. Small

B. Very large

C. None of the above

D. Large

6. What turn ratio (Np/Ns) of transformer is required to match 4 O speaker to a transistor having an output impedance of 8000 O ?
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A. None of the above

B. 2

C. 3

D. 7
7. When a transistor is cut off _________________?
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A. None of the above

B. Maximum voltage appears across transistor

C. Maximum current flows

D. Maximum voltage appears across load

8. The size of a power transistor is made considerably large to________________?
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A. Provide easy handling

B. None of the above

C. Dissipate heat

D. Facilitate connections

9. The driver stage usually employs_________________?
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A. Class A power amplifier

B. Push-pull amplifier

C. None of the above

D. Class C amplifier

10. Transformer coupling can be used in______________amplifiers?
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A. Only power

B. Only voltage

C. None of the above

D. Either power or voltage
11. Class C amplifiers are used as ___________________?
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A. AF amplifiers

B. None of the above

C. amplifiers

D. Detectors

12. Low efficiency of a power amplifier results in_________________?
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A. Less battery consumption

B. More battery consumption

C. Low forward bias

D. None of the above

13. A class A power amplifier uses _________________?
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A. None of the above

B. Three transistors

C. Two transistors

D. One transistor
14. Power amplifiers generally use transformer coupling because transformer permits______________?
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A. Distortionless output

B. Impedance matching

C. Cooling of the circuit

D. Good frequency response

15. What will be the collector efficiency of a power amplifier having zero signal power dissipation of 5 watts and a.c. power output of 2 watts ?
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A. 80%

B. 40%

C. 50%

D. 20%

16. If the gain versus frequency curve of a transistor amplifier is not flat, then there is distortion ?
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A. None of the above

B. Intermodulation

C. Frequency

D. Amplitude

17. ________________ coupling is generally employed in power amplifiers?
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A. Impedance

B. Transformer

C. RC

D. direct

18. A transformer coupled class A power amplifier has a load of 100 O on the secondary. If the turn ratio is 10:1, what is the value of load appearing on the primary?
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A. 20 kO

B. 100 kO

C. 10 kO

D. 5 kO

19. If the power rating of a transistor is 1W and collector current is 100mA, then maximum allowable collector voltage is________________?
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A. 100V

B. 10V

C. 1V

D. 20V

20. The output stage of a multistage amplifier is also called _________________-?
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A. Mixer stage

B. Power stage

C. Detector stage

D. F stage

21. Class _____________ operation gives the maximum distortion?
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A. A

B. AB

C. B

D. C
22. If a transistor is operated in such a way that output current flows for 60o of the input signal, then it is ______________ operation?
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A. Class B

B. None of the above

C. Class C

D. Class A

23. The class B push-pull circuit can deliver 100 W of a.c. output power. What should be the minimum power rating of each transistor ?
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A. 40 W

B. 20 W

C. 10 W

D. 80 W

24. The output transformer used in a power amplifier is a _____________ transformer?
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A. 1:1 ratio

B. None of the above

C. Step-down

D. Step-up

25. The disadvantage of impedance matching is that it _______________?
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A. Gives distorted output

B. None of the above

C. Requires a transformer

D. Gives low power output

26. The push-pull circuit must use ______________ operation?
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A. Class B

B. Class A

C. Class C

D. Class AB

27. In class A operation, the operating point is generally located_____________of the d.c. load line?
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A. None of the above

B. At cut off point

C. At the middle

D. At saturation point

28. For the same a.c. power output as above, what should be the minimum power rating of transistor for class B operation?
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A. 10 W

B. 8 W

C. 4 W

D. None of the above

29. A 2-transistor class B power amplifier is commonly called ______________ amplifier?
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A. Push-pull

B. Differential

C. Symmetrical

D. Dual

30. The most important consideration in power amplifier is __________________?
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A. To keep the transformer cool

B. None of the above

C. Collector efficiency

D. Biasing the circuit

31. The maximum efficiency of resistance loaded class A power amplifier is _________________?
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A. 50%

B. 30%

C. 5%

D. 25%
32. If the zero signal dissipation of a transistor is 1W, then power rating of the transistor should be at least___________________?
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A. 5 W

B. 33 W

C. 1 W

D. 75 W

33. The output stage of a multistage amplifier usually employs _________________?
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A. Class A power amplifier

B. Preamplifier

C. None of the above

D. Push-pull amplifier
34. The output stage of a multistage amplifier usually employs______________?
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A. Push-pull amplifier

B. None of the above

C. Preamplifier

D. Class A power amplifier

35. A class A power amplifier is sometimes called______________amplifier?
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A. Symmetrical

B. Single-ended

C. Differential

D. Reciprocating

36. The maximum collector efficiency of class B operation is ________________?
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A. 5%

B. 5%

C. 50%

D. 90%

37. An AF amplifier is shielded to ________________?
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A. Keep the amplifier cool

B. Prevent induction due to stray magnetic fields

C. Protect from rusting

D. None of the above

38. The maximum a.c. power output from a class A power amplifier is 10 W. What should be the minimum power rating of the transistor used ?
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A. 5 W

B. 10 W

C. 20 W

D. 15 W

39. The maximum efficiency of transformer coupled class A power amplifier is _______________?
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A. 80%

B. 50%

C. 45%

D. 30%

40. The pulsating d.c. applied to power amplifier causes________________?
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A. Hum in the circuit

B. Excessive forward voltage

C. Burning of transistor

D. None of the above