GATE EC 2002 Set 1 Q2.6 — Op-amp Circuits

The circuit in figure employs positive feedback and is intended to generate sinusoidal oscillation. If at a frequency $f_{0}, \mathrm{~B}(f)=\Delta \frac{V_{f}(f)}{V_{0}(f)}=\frac{1}{6} \angle 0^{\circ}$, then to sustain oscillation at this frequency