Push-Pull Class B Amplifier MCQ’s

This set of Analog Electronic Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Push-Pull Class B Amplifier”.

1. What is the output of a class B amplifier for sinusoidal input?
a) Sinusoidal amplifier
b) Half-sinusoidal
c) Sinusoidal with higher frequency
d) Square wave

2. How do we obtain sinusoidal output out of a class B amplifier?
a) By using non-sinusoidal inputs
b) By utilizing two transistors
c) By biasing it in the active region
d) By adding a capacitor to the output

3. Which of these is not true for a class B amplifier?
a) It has zero DC bias
b) They have an efficiency less than that of class A amplifiers
c) The quiescent power dissipation is zero
d) The conduction angle is only 180°

4. In a class B amplifier, it is found that DC power is 25W, find the ac power.
a) 10 W
b) 62.5 W
c) 25 W
d) 50 W

5. What is the disadvantage of a class B push-pull amplifier?
a) The efficiency reduces
b) The figure of merit increases
c) The cross-over distortion occurs
d) The Q-power dissipation is very large

6. Why does no DC current flow in the primary winding of the output transformer of class B push-pull amplifier?
a) Because DC currents from both transistors flow in opposite directions
b) Because the net impedance is very high to allow flow of current
c) The winding only allows AC current to flow
d) Current only flows in secondary winding due to the presence of load at that side

7. When is the maximum efficiency of class B amplifier achieved?
a) When VMAX = VCC
b) When two transistors are used
c) When VMIN = 0
d) Efficiency is always constant

8. Read statements and select the correct option below.

A: A push-pull amplifier decreases harmonic distortion
B: Output has half-wave symmetry

a) A and B are both correct and B is the correct reason for A
b) A is correct and B is incorrect
c) Both A and B are correct but B is not the correct reason for A
d) Both A and B are incorrect

9. Which of these is incorrect for complementary symmetry push-pull amplifiers?
a) During positive cycle NPN transistor conducts
b) It is easier to fabricate on IC
c) Size of the transformer required reduces
d) Efficiency and figure of merit are same as transformer coupled push-pull amplifier

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