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In a positive feedback system if the open loop gain is -100 and the feedback factor 1/10, calculate the closed loop gain.

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HPCL Engineer Instrumentation 11 Aug 2021 Official Paper
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  1. 11.11
  2. 9.09
  3. -11.11
  4. -9.09

Answer (Detailed Solution Below)

Option 4 : -9.09
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Detailed Solution

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Concept

The open loop gain is given by G(s) 

The feedback factor is given by H(s)

Hence the closed loop transfer function is given by 

The transfer function of the closed-loop transfer function, with a positive value of feedback gain, is given by,

Calculation

Given G(s)  = -100

H(s) = 1/10

The closed-loop transfer function is given by: 

 = -9.09

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