What is the effect of increasing gain in a root locus plot?

• A. Poles move towards infinity
• B. Poles move towards the right half-plane
• C. Poles move along the real axis
• D. Poles move along the locus path

Answer: (D)

Increasing gain in a root locus plot results in the poles moving along the locus path. The root locus represents the possible locations of the system's poles for varying values of gain. As the gain increases, the poles trace a specific, defined path in the complex plane, which may be characterized by both real and imaginary components.

The behavior of the poles is determined by the characteristics of the open-loop transfer function. As gain increases, one or more poles may migrate toward the zeros or away from them, depending on the configuration of the system. Understanding that the poles move along the predefined locus is crucial for predicting the system's stability and performance variations in response to changes in gain.

This movement can lead to different stability outcomes, as poles in the left-half plane indicate stable behavior, while those in the right-half plane represent instability.