Surface Charge Density Converter

About the surface charge density converter

Surface charge density (σ) is the charge per unit area on a 2D surface, measured in coulombs per square meter (C/m²) in SI. It governs the electric field just outside a conducting plate or capacitor electrode — by Gauss’s law, the field is σ/ε₀ above an infinite charged plane. Capacitor designers, MEMS engineers, and electrostatics problems all rely on this quantity.

Frequently asked questions

• What is the field above a charged plane? +

  For an infinite conducting plane, E = σ / ε₀ just outside the surface. For a thin non-conducting sheet, the field on each side is σ / (2ε₀).

• How does surface charge relate to capacitance? +

  In a parallel-plate capacitor, the charge per plate Q = σ × A, and the voltage is V = σ d / ε, where d is the gap and ε is the dielectric permittivity.