Question

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

• A. 90
• B. 100
• C. 9
• D. 10

Answer 1

Answer: (B)

100

Answer 2

The voltage gain of the amplifier with negative feedback is $A' = \frac{A}{1+\beta A}$ where, $A =$ voltage gain without feedback $??=$ feedback factor Here, $A' = 10, \,??= 9\% = 0.09$ $\therefore\quad10 = \frac{A}{1+0.09\,A}$ $10 + 0.9\,A = A$ $A\left(1 - 0.9\right) = 10$ $A = \frac{10}{0.1} = 100$