Correct Answer - Option 1 : less than zero
The Nyquist plot of a loop transfer function G(jω) H(jω) of a system encloses the (-1, j0) point.
That means the given system is unstable, hence the gain margin is negative.
Important Points:
- For a stable system, gain margin and phase margin are positive
- For an unstable system, gain margin and phase margin are negative
- For a marginally stable system, gain margin and phase margin are equal to zero.