Question

The phase shift network will produce a phase shift of 180 degrees at ___________

(a) Three different frequencies

(b) One frequency

(c) Two different frequencies

(d) Infinitely many frequencies

I had been asked this question at a job interview.

My question is based upon RC Phaseshift Oscillator in section Oscillators of Analog Circuits

Answer 1

Right option is (b) One frequency

To explain: The phase shift oscillator will produce a phase shift of 180 degrees only at a particular frequency by which it is meant to oscillate.