# Electronic Devices and Circuits Questions and Answers – Class A Large Signal Amplifiers

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses 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

Explanation: 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

Explanation: 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

Explanation: 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 load.
a) True
b) False

Explanation: 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

Explanation: Since class A amplifiers use basic transistor, even the noise signal will get amplified when the noise signal exists in input.
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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

Explanation: 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

Explanation: 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%

Explanation: 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

Explanation: 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

Explanation: 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.

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