Angle of departure is calculated for:

• A. Real poles
• B. Complex poles
• C. Real zeros
• D. Gain values

Answer: (B)

The angle of departure is specifically associated with complex poles in the context of control systems and stability analysis. Complex poles appear in conjugate pairs and introduce oscillatory behavior to the system response. The angle of departure is a concept that determines how the roots of the characteristic equation will behave as they move away from the poles in the s-plane.

When dealing with complex poles, the angle of departure is critical for analyzing system stability, as it provides insight into the direction in which the system's response will move when perturbed. This is particularly important in root locus techniques, where understanding the behavior of complex poles allows engineers to predict how changes in system parameters will affect stability and transient response.

Real poles, on the other hand, do not have an angle of departure since they do not contribute to oscillatory behavior; they simply lead to exponential decay or growth without any associated angular motion. Real zeros affect the shape of the root locus but do not have angles of departure. Gain values can influence the overall system behavior but are not related to the direct calculation of an angle of departure in the same manner that complex poles are.

Thus, the correct focus on complex poles in determining the angle of departure reflects their unique role in influencing the dynamic behavior of systems in control theory