RLC filter terminology: which property of an electrical circuit best describes its ability to respond strongly to selected (desired) frequencies while rejecting or greatly attenuating all other frequencies?

Introduction / Context:
In RLC circuits and filters, engineers often need a concise term for how well a network responds to certain frequencies and rejects others. This capability is crucial in radio receivers, instrumentation, and audio crossovers. The question asks for the correct property name that captures this frequency discrimination ability.

Given Data / Assumptions:

• Circuit context: linear time-invariant RLC or active filter networks.
• Desired behavior: pass (or amplify) a target band and suppress out-of-band content.
• No specific numeric values are required; this is a definition/terminology check.

Concept / Approach:
“Selectivity” describes how selectively a circuit accepts desired frequencies while rejecting undesired ones. It is a qualitative attribute, often quantified by shape factor, out-of-band attenuation, and skirt steepness around the passband or notch. While bandwidth and quality factor are related metrics (e.g., Q = f0 / BW for narrowband resonators), they do not by themselves state the overall ability to reject out-of-band signals; sensitivity refers to signal magnitude response, not frequency discrimination.

Step-by-Step Solution:

Verification / Alternative check:
Receiver specifications list “selectivity” as the measure of adjacent-channel rejection, often using dB attenuation at offsets from the center frequency. This aligns precisely with the verbal definition in the stem.

Why Other Options Are Wrong:

• Bandwidth: measures the width of the passband but not overall rejection behavior.
• Sensitivity: indicates required input level for a given output; not frequency discrimination.
• Quality factor: relates to resonance sharpness; a high Q suggests narrow bandwidth but is not the general property name.
• Dynamic range: span between minimum detectable and maximum allowable signal; not about frequency selectivity.

Common Pitfalls:
Equating narrow bandwidth or high Q with complete selectivity; ignoring skirt steepness and stopband attenuation which are also part of real-world selectivity performance.

Final Answer:
Selectivity