Terminology » RF Basics » Dielectric vs. Conductor: Key Differences Explained

Dielectric vs. Conductor: Key Differences Explained

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This article breaks down the core differences between dielectric and conductor materials, covering their fundamental properties and behavior.

Conductor

  • A conductor is a material that readily allows the flow of electric charge.
  • The electrons in a conductor are loosely bound, enabling them to move freely and carry an electric current.
  • Common conductor materials include: copper, aluminum, gold, silver, and steel.

Difference between Dielectric and Conductor

Image showing the difference between a Dielectric and a Conductor.

Dielectric

  • A dielectric (also known as an insulator) is a material that does not easily conduct electric current.

  • Electrons in a dielectric material are tightly bound to their atoms, restricting their movement.

  • While dielectrics don’t conduct, they can be polarized by an external electric field (E ext). This polarization occurs as the electric field causes a slight shift in the positions of the atoms or molecules within the material. The charges do not migrate, they are just slightly repositioned.

  • Common dielectric materials include: mica, teflon, fused quartz, titanium dioxide, paper, glass, diamond, dry wood, benzene, and glycerin.

The figure below depicts a parallel plate capacitor with two conductor plates separated by a dielectric material.

The Capacitance, C = K*C0

Where, C0 = ε0 * A/d

  • “A” is the area of the plate
  • “d” is the distance between the plates.
  • ε0 is the permittivity of air
  • K is the dielectric constant or relative permittivity of the dielectric

Dielectric vs. Conductor: A Detailed Comparison

The following table summarizes the key differences between dielectric and conductor materials:

ParameterDielectricConductor
FunctionActs as an insulator, preventing current flow.Acts as a conductor, allowing current to flow easily.
Electric Field (E) DirectionParallel to the surface of the dielectric material.Perpendicular to the surface of the conductor material.
Electric Field PresencePresent inside the material.Not present inside the material.
Free Charge CarriersDielectric substances do not contain free charge carriers.Conductor substances contain a large number of free charge carriers.
Temperature & ConductivityConductivity increases with temperature.Conductivity decreases with temperature.
Bulk ConductivitySmallLarge
PolarizationElectric polarization dominates.No electric polarization up to 1016 Hz
ExamplesAir, plastic, wood, rubber, Mica, etc.Copper, gold, silver, iron, aluminum, etc.