Question

A system has poles at 0.01 Hz, 1 Hz and 80 Hz, zeros at 5 Hz, 100 Hz, and 200 Hz. The approximate phase of the system response at 20 Hz is

• A. \( + 90^\circ \)
• B. \( - 90^\circ \)
• C. \( + 180^\circ \)
• D. \( - 180^\circ \)

Hint:

Poles contribute negative phase and zeros contribute positive phase in Bode plots.

Answer 1

The Correct Option is B

The phase contribution of poles and zeros at 20 Hz is calculated as: \[ {Phase contribution of poles} = -90^\circ, \quad {Phase contribution of zeros} = +0^\circ \] Thus, the total system phase at 20 Hz is \(-90^\circ\).