Amplifiers with Negative Feedback Multiple Choice Questions (MCQs) & Answers

Amplifiers with Negative Feedback Multiple Choice Questions(MCQs) & Answers Amplifiers with Negative Feedback

Amplifiers with Negative Feedback Multiple Choice Questions(MCQs)& Answers

CONCEPTS & THEORIES

amplifiers-with-negative-feedback

About Negative Feedback Amplifier

A Negative-feedback amplifier is an electronic amplifier that subtracts a fraction of its output from its input, so that negative feedback opposes the original signal.It is the method of feeding a portion of the amplified output to the input but in opposite phase. The applied negative feedback can improve its performance and reduces sensitivity to parameter variations due to manufacturing or environment.
There are two main types of negative feedback circuits. They are −
-Negative Voltage Feedback
-Negative Current Feedback

Negative Voltage Feedback


In this method, the voltage feedback to the input of amplifier is proportional to the output voltage. This is further classified into two types. They are −
-Voltage-series feedback
-Voltage-shunt feedback

Negative Current Feedback


In this method, the voltage feedback to the input of amplifier is proportional to the output current. This is further classified into two types.They are −
-Current-series feedback
-Current-shunt feedback

Effects of negative feedback on an amplifier


The major Effects that are introduced by negative feedback are:
-Reduced sensitivity to changes in open loop gain.
-Increases the bandwidth – While open loop amplifier have high gain, they generally have low bandwidth.
-Increase input impedance and decreases output impedance – Basically makes the amplifier closer to an ideal amplifier
-Decreases the output noise of the amplifier
-Reduces the impact of noise from components inside the loop
-Corrects for non-linearity inside the loop – Distortion is reduced

QUESTIONS

Amplifiers with Negative Feedback Multiple Choice Questions(MCQs)& Answers

1 The gain of an amplifier without feedback is 100 db. If a negative feedback of 3 db is applied, the gain of the amplifier will become …………..
A 5 db
B 300 db
C 103 db
D 97 db

Answer: 97 db
2 The gain of an amplifier with feedback is known as ………….. gain
A Resonant
B Open loop
C Closed loop
D None of the above

Answer: Closed loop
3 A Negative-feedback amplifier is an …….. amplifier.
A Magnetic
B Electronic
C Electromagnetic
D None of the above

Answer:Electronic
4 The voltage gain of an emitter follower is ………..
A Much less than 1
B Approximately equal to 1
C Greater than 1
D None of the above

Answer: Approximately equal to 1
5 The output impedance of an emitter follower is ……….
A High
B Very high
C Almost zero
D Low

Answer: Low
6 Emitter follower is used for …………
A Current gain
B Impedance matching
C Voltage gain
D None of the above

Answer: Impedance matching
7 If the feedback fraction of an amplifier is 0.01, then voltage gain with negative feedback is approximately………..
A 500
B 100
C 1000
D 5000

Answer: 100
8 Emitter follower is a ……………….. circuit
A Voltage feedback
B Current feedback
C Both voltage and current feedback
D None of the above

Answer: Current feedback
9 When a negative voltage feedback is applied to an amplifier, its bandwidth……….
A Is increased
B Insufficient data
C Is decreased
D Remains the same

Answer: Is increased
10 When current feedback (negative) is applied to an amplifier, its input impedance …………..
A Remains the same
B Is decreased
C Is increased
D None of the above

Answer: Is decreased
11 The value of negative feedback fraction is always …………….
A Less than 1
B More than 1
C Equal to 1
D None of the above

Answer: Less than 1
12 An emitter follower has ………… input impedance
A Zero
B Low
C High
D None of the above

Answer: High
13 If voltage feedback (negative) is applied to an amplifier, its output impedance …………..
A Remains the same
B Is increased
C Is decreased
D None of the above

Answer: Is decreased
14 When current feedback (negative) is applied to an amplifier, its output impedance ……..
A Is increasedIs increased
B Is decreased
C Remains the same
D None of the above

Answer: Is increasedIs increased
15 Negative feedback is employed in ……………..
A Amplifiers
B Rectifiers
C Oscillators
D None of the above

Answer: Amplifiers
16 When voltage feedback (negative) is applied to an amplifier, its input impedance ………….
A Is increased
B Is decreased
C Remains the same
D None of the above

Answer: Is increased
17 A feedback circuit usually employs ……………… network
A Capacitive
B Resistive
C Inductive
D None of the above

Answer: Resistive
18 If the output of an amplifier is 10 V and 100 mV from the output is fed back to the input, then feedback fraction is ………..
A 10
B 1
C 01
D 15

Answer: 01
19 When negative voltage feedback is applied to an amplifier, its voltage gain ……………….
A Is increased
B Is reduced
C Remains the same
D None of the above

Answer: Is reduced
20 Permanent Magnetic speakers commonly used in………..
A Radio signal Tower
B Radio
C Transformer
D All of the above

Answer: Radio

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