Capacitor structure — identify the non-conductive medium: The basic capacitor consists of two conductive plates separated by what kind of material?

Introduction / Context:
All capacitors share a core structure: two conductors separated by a non-conductive medium that stores energy in an electric field. Recognizing this medium’s role is essential to understanding capacitance, leakage, breakdown, and frequency behavior.

Given Data / Assumptions:

• Parallel-plate conceptual model for clarity.
• Two conductive electrodes (plates).
• Non-conductive separator between plates.

Concept / Approach:
The separator is the dielectric: an insulating material characterized by permittivity (epsilon) and breakdown strength. Its permittivity influences capacitance (C ∝ epsilon), and its loss tangent and stability affect AC behavior and temperature/frequency characteristics. Common dielectrics include air, paper, ceramics, mica, polymers, and oxide layers (e.g., in electrolytics).

Step-by-Step Solution:

Verification / Alternative check:
Textbook definitions of capacitance explicitly assume an insulating dielectric layer between plates; replacing it with a conductor collapses the plates into a short circuit (no energy storage).

Why Other Options Are Wrong:

• A conductor / an electrode: those are the plates themselves, not the separator.
• A spacer: a generic mechanical term; in capacitors the proper term is dielectric, which provides electrical insulation and field storage.

Common Pitfalls:
Using “spacer” or “insulator” loosely; “dielectric” is the precise term in capacitor theory.

Final Answer:
A dielectric.