Question

The final value theorem is applicable if __________

(a) Poles lie on right half of s plane

(b) Poles lie on left half of s plane

(c) Poles lie on the imaginary axis

(d) Zeros lie on left half of s plane

The question was posed to me during an online interview.

Origin of the question is Laplace Transform in chapter Control System Applications of MATLAB

Answer 1

Correct choice is (b) Poles lie on left half of s plane

For explanation: If poles don’t lie on the left half of s-plane, the system is not stable. An unstable system yields an erroneous final value which i.e an erroneous steady state response. They also cannot lie on the imaginary axis. Hence, the theorem is applicable only in case of poles lie on right half of s plane.