Question

The limit cycles describe the ____ of non-linear systems

• A. Linearity
• B. Stability
• C. Causality
• D. Oscillations

Hint:

Limit cycles are closed trajectories in the phase plane of a non-linear system.
They represent periodic, self-sustained oscillations of fixed amplitude and frequency.
Stable limit cycles attract nearby trajectories, while unstable limit cycles repel them.
They are a hallmark of non-linear system behavior and cannot occur in linear time-invariant systems (which can only have damped oscillations, undamped oscillations around an equilibrium, or divergent responses if unstable).

Answer 1

The Correct Option is D

A limit cycle is a characteristic behavior of some non-linear dynamical systems. It represents an isolated closed trajectory in the phase space.
If system trajectories near the limit cycle converge towards it (from inside or outside), it is a stable limit cycle, representing a self-sustained oscillation with a fixed amplitude and frequency.
If trajectories move away from it, it is an unstable limit cycle. Limit cycles are fundamentally related to oscillatory behavior in non-linear systems. They also have implications for stability (a stable limit cycle is a form of bounded output, but not necessarily stable in the Lyapunov sense around an equilibrium point if that equilibrium is unstable). (a) Linearity: Limit cycles are a feature of non-linear systems. (b) Stability: Limit cycles are related to stability; a stable limit cycle is a form of bounded oscillatory behavior. An unstable limit cycle can separate regions of stability and instability. (c) Causality: Not directly described by limit cycles. (d) Oscillations: Limit cycles inherently describe periodic, self-sustained oscillations in non-linear systems. Given the options, "Oscillations" is the most direct phenomenon described by limit cycles. They are a particular type of oscillation. While related to stability, the primary manifestation is oscillatory behavior. \[ \boxed{\text{Oscillations}} \]