Conductors in electrostatic equilibrium
Equilibrium field vanishes in the conducting material, including a charged conductor.
Key knowledge
In the ideal macroscopic electrostatic conductor model, electric field is zero in the conducting material and each connected conductor is at a constant potential. Excess charge occupies its surfaces; a smooth surface in vacuum has E_out=σ_s n/ε₀ immediately outside. A cavity can contain a field if it contains charge, so field-free material does not guarantee an empty-field cavity under every condition.
Values and equations
E_material=0; E_out=σ_s n/ε₀
- E_material,E_out
- Macroscopic electric field in conductor material and just outside its vacuum boundary V m⁻¹
- σ_s
- Signed surface charge density C m⁻²
- n
- Outward unit normal 1
- ε₀
- Vacuum permittivity F m⁻¹
Conditions and scope
- Electrostatic equilibrium, ideal conductor and smooth boundary in vacuum; n points out of conductor material.
- Surface includes inner cavity walls when internal charges induce them. Current-carrying resistive conductors, rapidly changing fields, atomic-scale surface structure and dielectric interfaces require other models.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Samuel J. Ling, Jeff Sanny and William Moebs — OpenStax, Rice University, University Physics (2016)2 sources
- University Physics Volume 2, §6.4: conductors in electrostatic equilibriumSamuel J. Ling, Jeff Sanny and William Moebs — OpenStax, Rice University, University Physics (2016)Textbook chapter
- University Physics Volume 2, §7.4: determining field from potentialSamuel J. Ling, Jeff Sanny and William Moebs — OpenStax, Rice University, University Physics (2016)Textbook chapter
Evidence and review
Read §6.4 equilibrium field, Gauss surface-charge and normal exterior-field discussion plus §7.4 E=−∇V. Constant potential follows the zero field; distinguish conductor material from a charge-containing cavity.
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