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For a unity feedback control system, if its open-loop transfer function is given by , then its gain margin will be

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  1. 20 dB
  2. 40 dB
  3. 60 dB
  4. 80 dB

Answer (Detailed Solution Below)

Option 2 : 40 dB
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Detailed Solution

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Concept:

The gain margin is always calculated at the phase Crossover frequency (ωpc)

The phase Crossover frequency (ωpc) is calculated as:

Gain margin 

Calculation:

Given:

∠G(jω)H(jω) = -180°

 rad/sec

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