Question #03d44

Question

2406 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-11-22T00:00:12

The answer is selection: a) 5

The general equation for a positive feedback system is:

$A_{c} = \frac{A_{ol}}{1 - β A_{ol}} [1]$ $A_"c" = A_"ol"/(1 - betaA_"ol")" [1]"$

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

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

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

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

$10 = \frac{A_{ol}}{1 - 0.1 A_{ol}}$ $10 = A_"ol"/(1- 0.1A_"ol")$

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

$10 - A_{ol} = A_{ol}$ $10- A_"ol" = A_"ol"$

$2 A_{ol} = 10$ $2A_"ol"=10$

$A_{ol} = 5$ $A_"ol" = 5$

The answer is selection: a) 5