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

Options

A. 10
B. 20
C. 100
D. 90

Answer

C

Explanation

For a feedback oscillator , the voltage gain `(A_f)` is given by `A_f=A/(1-Abeta)`
where `beta` is the feedback factor and A is the voltage gain without feedback.
In this case, `beta=-9/10, A_f` = 10
`therefore 10=A/(1+10xx9/10)=A/(1+9)=A/10`
`therefore` A=100