Control Systems: Match Concepts to Their Descriptions List I A. Very low response at very high frequencies B. Over shoot C. Synchro-control transformer output List II Low-pass system Velocity damping Natural frequency Phase-sensitive modulation Damping ratio

Introduction / Context:
This matching problem revisits three common control-engineering ideas: the frequency response shape of a low-pass system, the meaning of overshoot in transient response, and the characteristic output of a synchro-control transformer. Knowing these associations strengthens intuition for both frequency-domain and time-domain behavior, as well as electromechanical sensor interfaces.

Given Data / Assumptions:

• A: Very low response at very high frequencies.
• B: Overshoot in a step response.
• C: Synchro-control transformer output signal nature.
• List II contains: Low-pass system, Velocity damping, Natural frequency, Phase-sensitive modulation, Damping ratio.

Concept / Approach:

A low-pass system attenuates high-frequency content; therefore its gain is small (very low response) at very high frequencies. Step-response overshoot depends primarily on the damping ratio (zeta) of the dominant second-order dynamics. A synchro-control transformer is inherently phase sensitive; its output depends on the phase (angle) between rotor and stator fields and resembles phase-sensitive modulation of an error angle.

Step-by-Step Solution:

Verification / Alternative check:

Second-order step-response formulas show peak overshoot M_p = exp(−πζ / sqrt(1 − ζ^2)), directly linking overshoot to damping ratio. Synchro/control-transformer schematics and small-angle approximations (V_out ≈ K * θ_error) confirm phase-sensitive behavior. Bode plots of low-pass filters demonstrate large attenuation as frequency increases.

Why Other Options Are Wrong:

Velocity damping (2) is a particular damping implementation, not the general parameter determining overshoot. Natural frequency (3) sets oscillation speed, but overshoot magnitude hinges mainly on damping ratio. Other pairings misrepresent the fundamental definitions.

Common Pitfalls:

Confusing the cause (damping ratio) with the mechanism (velocity feedback) for overshoot; also, mistaking a band-pass/notch behavior for low-pass when describing high-frequency attenuation.

Final Answer:

A-1, B-5, C-4