Question #03d44

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Answer 1 · 2017-11-22T00:00:12

The answer is selection: a) 5

The general equation for a positive feedback system is:

$A_"c" = A_"ol"/(1 - betaA_"ol")" [1]"$

Where $A_"c"$ is the closed loop gain, $A_"ol"$ is open loop gain, and, $beta$ is the gain of the feedback circuit.

We are given that $A_"c" = 10$

And the phrase; "10% positive feedback" implies that $beta = 0.1$

Substitute these values into equation [1] and solve for $A_"ol"$ :

$10 = A_"ol"/(1- 0.1A_"ol")$

$10(1- 0.1A_"ol") = A_"ol"$

$10- A_"ol" = A_"ol"$

$2A_"ol"=10$

$A_"ol" = 5$

The answer is selection: a) 5