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

Options

A. 90
B. 10
C. 1.25
D. 100

Answer

D

Explanation

Voltage gain with feedback and `beta` is negative feedback.
Given `A_(vf)=10,beta=90%=(9)/(100)`
`10=(A_(v))/(1+(9)/(100)A_(v))or10+(9)/(10)A_(v)=A_(v)`
or `0.1A_(v)=10orA_(v)=100`