300+ TOP Transistor audio Power amplifier Questions and Answers pdf | MCQs

TRANSISTOR  AUDIO POWER AMPLIFIERS Questions :-

1. The output stage of a multistage amplifier is also called ……………

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Mixer stage
Power stage
Detector stage
F stage
Ans : 2

2. ………………. coupling is generally employed in power amplifiers

Transformer
RC
direct
Impedance
Ans : 1

3. A class A power amplifier uses …………

Two transistors
Three transistors
One transistor
None of the above
Ans : 3

4. The maximum efficiency of resistance loaded class A power amplifier is ……..

5%
50%
30%
25%
Ans : 4

5. The maximum efficiency of transformer coupled class A power amplifier is ………………

30%
50%
80%
45%
Ans : 2

6. Class……. power amplifier has the highest collector efficiency

C
A
B
AB
Ans : 1

7. Power amplifiers handle …………. signals compare to voltage amplifiers

Small
Very small
Large
None of the above
Ans : 3

8. In class A operation, the operating point is generally located ………. of the d.c. load line.

At cut off point
At the middle
At saturation point
None of the above
Ans : 2

9. Class C amplifiers are used as …………….

AF amplifiers
Detectors
F. amplifiers
None of the above
Ans : 3

10. A power amplifier has comparatively …………….. ß

Small
Large
Very large
None of the above
Ans : 1

11. The maximum collector efficiency of class B operation is ……………..

50%
90%
5%
5%
Ans : 4

12. A 2-transistor class B power amplifier is commonly called ……….. amplifier

Dual
Push-pull
Symmetrical
Differential
Ans : 2

13. If a transistor is operated in such a way that output current flows for 60o of the input signal, then it is …………… operation

Class A
Class B
Class C
None of the above
Ans : 3

14. If the zero signal dissipation of a transistor is 1W, then power rating of the transistor should be at least ……………….

5 W
33 W
75 W
1 W
Ans : 4

15. When a transistor is cut off……………..

Maximum voltage appears across transistor
Maximum current flows
Maximum voltage appears across load
None of the above
Ans : 1

16. A class A power amplifier is sometimes called ………….. amplifier

Symmetrical
Single-ended
Reciprocating
Differential
Ans : 2

17. Class ………….. operation gives the maximum distortion

A
B
C
AB
Ans : 3

18. The output stage of a multistage amplifier usually employs ………..

Push-pull amplifier
Preamplifier
Class A power amplifier
None of the above
Ans : 1

19. The size of a power transistor is made considerably large to …………

Provide easy handling
Dissipate heat
Facilitate connections
None of the above
Ans : 2

20. Low efficiency of a power amplifier results in ……………….

Low forward bias
Less battery consumption
More battery consumption
None of the above
Ans : 3

21. The driver stage usually employs………….

Class A power amplifier
Push-pull amplifier
Class C amplifier
None of the above
Ans : 1

22. If the power rating of a transistor is 1W and collector current is 100mA, then maximum allowable collector voltage is ………..

1V
100V
20V
10V
Ans : 4

23. When no signal is applied, the approximate collector efficiency of class A power amplifier is …….

10%
0%
25%
50%
Ans : 2

24. 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?

20%
80%
40%
50%
Ans : 3

25. 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?

1 W
2 W
4 W
None of the above
Ans : 1

26. 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 ?

10 W
15 W
5 W
20 W
Ans : 4

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

10 W
4 W
8 W
None of the above
Ans : 2

28. The push-pull circuit must use …………… operation

Class A
Class C
Class B
Class AB
Ans : 3

29. 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?

20 W
40 W
10 W
80 W
Ans : 1

30. What turn ratio (Np/Ns) of transformer is required to match 4 O speaker to a transistor having an output impedance of 8000 O?

2
7
3
None of the above
Ans : 2

31. 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?

5 kO
20 kO
100 kO
10 kO
Ans : 4

32. Power amplifiers generally use transformer coupling because transformer permits……..

Cooling of the circuit
Impedance matching
Distortionless output
Good frequency response
Ans : 2

33. Transformer coupling can be used in …………… amplifiers

Either power or voltage
Only power
Only voltage
None of the above
Ans : 1

34. The output transformer used in a power amplifier is a ……………. transformer

1:1 ratio
Step-up
Step-down
None of the above
Ans : 3

35. The most important consideration in power amplifier is ………..

Biasing the circuit
Collector efficiency
To keep the transformer cool
None of the above
Ans : 2

36. An AF amplifier is shielded to …………

Keep the amplifier cool
Protect from rusting
Prevent induction due to stray magnetic fields
None of the above
Ans : 3

37. The pulsating d.c. applied to power amplifier causes ……………..

Burning of transistor
Hum in the circuit
Excessive forward voltage
None of the above
Ans : 2

38. The disadvantage of impedance matching is that it ………………….

Gives distorted output
Gives low power output
Requires a transformer
None of the above
Ans : 1

39. If the gain versus frequency curve of a transistor amplifier is not flat, then there is distortion.

Amplitude
Intermodulation
Frequency
None of the above
Ans : 3

40. The most costly coupling is ……………… coupling

RC
Direct
Impedance
Transformer
Ans : 4

TRANSISTOR  AUDIO POWER AMPLIFIERS Questions and Answers pdf free download :-