Q. The voltage gain of an amplifier with 9% negative feedback is 10. The voltage gain without feedback will be
A) 1.25
B) 100
C) 90
D) 10
Explanation
(b) Amplification with negative feedback is $A^{'} = \frac{A}{1 + \beta A}$
Where $\beta =$ fraction of output feedback to input
$\because\beta = \frac{9}{100} = 0.09$ and $A' = 10$
$\Rightarrow 10 = \frac{A}{1 + 0.09A} \Rightarrow A = 100$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.