250+ TOP MCQs on Class A Large Signal Amplifiers and Answers

Electronic Devices and Circuits Multiple Choice Questions on “Class A Large Signal Amplifiers”.

1. Why do we use CE amplifier as a large signal class a amplifier?
A. It has very high output impedance
B. It has very high input impedance
C. It has very high voltage gain
D. It is very much stable
Answer: C
Clarification: Since CE amplifier has reasonably high voltage gain and hence can work with high voltage or large signals.

2. What does class A amplifier do?
A. Delivers KV of voltage to load
B. Delivers KW of power
C. Delivers Kilo Pascal pressure
D. Delivers more resistance
Answer: B
Clarification: Class A always delivers more power to load because of a larger current delivered from the transistor.

3. What is the efficiency of Class A amplifiers?
A. 30 or less
B. 50 or less
C. 100
D. 75
Answer: A
Clarification: Since in Class A amplifiers distortion is more and as it requires tuned circuit as load, the efficiency is very low.

4. An ideal large signal amplifier delivers 100% DC power to its loaC.
A. True
B. False
Answer: A
Clarification: In an ideal case, no distortion occurs, that is noise effects are completely ignored, hence it gives 100% efficiency.

5. Which of the following statement is true about class A amplifiers?
A. They are weak against distortions
B. They supress noise signals
C. More efficient
D. Delivers 100% power to load
Answer: A
Clarification: Since class A amplifiers use basic transistor, even the noise signal will get amplified when the noise signal exists in input.

6. Why there is a need for heat sinks in Class A amplifier?
A. To control the external temperature
B. To avoid temperature changes affecting the transistor
C. To control heat dissipation
D. To increase output resistance
Answer: C
Clarification: When even no input is given to class A amplifiers, it produces some current to load, and hence heat sinks are required to avoid this.

7. Basic operation of Class A amplifiers____________
A. Crossover distortion
B. Law of Conservation of energy
C. Millers law
D. Switching transistor theory
Answer: D
Clarification: The class A amplifier is the simplest form of power amplifier that uses the switching transistor in the standard common emitter configuration.

8. If DC power for a Class A amplifier is 500W and AC power is 150W, what is its efficiency?
A. 50%
B. 75%
C. 20%
D. 30%
Answer: D
Clarification: efficiency=AC POWER/DC POWER
Efficiency=150/500=3/10
In percentage 3*100/10=30%.

9. Which of the following technique is used to increase the efficiency of class A amplifier?
A. By using FET
B. By using PNP transistor
C. By using matched transformers as load
D. By using potentiometers as load
Answer: C
Clarification: We can increase the efficiency of class A amplifier by using load matching concept, hence a pair of matched transformer can be used as load which in turn increases the efficiency.

10. What is the conduction angle of class A amplifier?
A. 90
B. 180
C. 270
D. 360
Answer: D
Clarification: Since the amplifier is always On, it conducts all the current waveform which can be used to state that it has 360 degree conduction angle.