Coil parasitics — the inherent DC resistance of an inductor's wire winding is called what?

Introduction / Context:
Real inductors are not ideal. In addition to inductance, they exhibit losses and parasitic elements. One important parameter is the ohmic resistance of the copper (or aluminum) wire itself, which affects efficiency, Q factor, and temperature rise. This question asks for the standard term used for that inherent resistance.

Given Data / Assumptions:

• The element is a coil of conductive wire.
• We are discussing its DC property (not frequency-dependent skin or proximity effects).
• Terminology should match common datasheet language.

Concept / Approach:
The resistance of the wire making up the coil, measured at DC, is called winding resistance (sometimes R_w or DCR for “DC resistance”). It is separate from the frequency-dependent increase in effective resistance caused by skin effect and proximity effect, often described as AC resistance or ESR in the context of power magnetics. Winding resistance contributes I^2 * R losses and lowers Q = X_L / R_total at a given frequency.

Step-by-Step Solution:

Verification / Alternative check:
Check typical inductor datasheets: “Inductance L,” “DCR (mΩ),” “Q at frequency,” and “SRF” are commonly listed. DCR equals the winding resistance at room temperature and rises with conductor temperature.

Why Other Options Are Wrong:

• Permeability: A property of core material, not conductive loss.
• Reactance: Imaginary opposition X_L = 2 * pi * f * L, not a real loss.
• AC resistance: A frequency-dependent effective resistance; the stem asks for inherent (DC) resistance.

Common Pitfalls:
Equating ESR/AC resistance with the DC winding resistance; ESR typically exceeds DCR at higher frequencies due to skin and proximity effects.

Final Answer:
winding resistance is the inherent DC resistance of the coil wire.