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Current Electricity

Question
CBSEENPH12040041
Wired Faculty App

The voltage gain of an amplifier with 9% negative feedback is 10. The voltage gain without feedback will be

  • 90

  • 10

  • 1.25

  • 100

Solution

D.

100

The process of injecting a fraction of output energy of some device back to the input is known as feedback. when the feedback energy (voltage or current) is out of phase with the input signal and thus opposes it, it is called negative feedback.
Voltage gain with feedback is
straight A subscript vf space equals space fraction numerator straight A subscript straight v over denominator 1 space plus βA subscript straight v end fraction where space straight A subscript straight v space is space voltage space gain space without space feedback space and space straight beta space is space negative space feedback. Given comma space straight A subscript vf space equals space 10 comma space straight beta space equals space 9 percent sign space equals space 9 over 100 therefore comma space 10 space equals space fraction numerator straight A subscript straight v over denominator 1 plus begin display style 9 over 100 end style straight A subscript straight v end fraction or space 10 space plus space 9 over 10 straight A subscript straight v space equals space straight A subscript straight v space equals space 100

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