Q. When $A$ is the internal stage gain of an amplifier and $\beta$ is the feedback ratio, then the amplifier becomes as oscillator if
A) $\beta$ is negative and magnitude of $\beta = A/2$
B) $\beta$ is negative and magnitude of $\beta = 1/A$
C) $\beta$ is negative and magnitude of $\beta = A$
D) $\beta$ is positive and magnitude of $\beta = 1/A$
Explanation
(d) The conditions for a circuit to oscillate are (i) the feedback is positive (ii) the fraction of the output voltage feedback $ie,\ \beta = \frac{1}{A}\ ie,\ $the reciprocal of the voltage gain without feedback.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.