Maximum efficiency of class B power amplifier is 50%. True False Maximum efficie

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Question
Maximum efficiency of class B power amplifier is 50%.
Options
A. True
B. False

Correct Answer

False

Explanation

Maximum efficiency for class B-operation can be 78.5% .

Analog Electronics problems

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1. Assertion (A): CE amplifier is the most widely used BJT amplifier
Reason (R): CE amplifier has zero phase difference between input and output
Options
A. Both A and R are correct and R is correct explanation for A
B. Both A and R are correct but R is not correct explanation for A
C. A is correct R is wrong
D. A is wrong R is correct

2. For a base current of 10 ?A, what is the value of collector current in common emitter if ?_dc = 100
Options
A. 10 ?A
B. 100 ?A
C. 1 mA
D. 10 mA

3. An RC coupled amplifier has an open loop gain of 200 and a lower cutoff frequency of 50 Hz. If negative feedback with ? = 0.1 is used, the lower cut off frequency will be
Options
A. about 50 Hz
B. about 5 Hz
C. about 2.38 Hz
D. about 70.5 Hz

4. The input impedance of op-amp circuit of figure is
Options
A. 120 k ohm
B. 110 k ohm
C. infinity
D. 10 k ohm

5. For a system to work, as oscillator the total phase shift of the loop gain must be equal to
Options
A. 90�
B. 45�
C. 270�
D. 360�

7. S_i transistor of following figure has a = 0.9 and I_CE= 0, V_EE = 5 V and V_CC = 13 V, then R_E will be if I_EQ = 1 mA
Options
A. 3 k?
B. 4 k?
C. 5 k?
D. 4.3 k?

9. The load impedance Z_L of a CE amplifier has R and L in series. The phase difference between output and input will be
Options
A. 180�
B. 0
C. more than 90� but less than 180�
D. more than 180� but less than 270�

10. An amplifier with loop gain A? will be more stable for value of A? as
Options
A. 0.95
B. 0.7
C. 1.2
D. 1.5

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