Ohmic wave attenuation and skin depth
For a homogeneous nonmagnetic ohmic medium with real ε and σ, a wave exp(ikz−iωt) satisfies k²=μ₀εω²+iμ₀σω.
Key knowledge
For a homogeneous nonmagnetic ohmic medium with real ε and σ, a wave exp(ikz−iωt) satisfies k²=μ₀εω²+iμ₀σω. In the good-conductor regime σ≫εω at ω>0, k≈(1+i)/δ with δ=√[2/(μ₀σω)]. Field amplitude decays as exp(−z/δ); intensity decays twice as rapidly in the exponent.
Values and equations
k²=μ₀εω²+iμ₀σω; δ=√[2/(μ₀σω)]; k≈(1+i)/δ
- k
- Complex propagation wavenumber m⁻¹
- δ
- Field-amplitude skin depth m
- ω
- Positive angular frequency rad s⁻¹
- σ
- Real Ohmic conductivity S m⁻¹
- ε
- Absolute electric permittivity F m⁻¹
- μ₀
- Vacuum permeability H m⁻¹
- z
- Depth into medium m
- t
- Time s
- i
- Imaginary unit
Conditions and scope
- Linear local isotropic constitutive model, μ=μ₀, positive approximately real conductivity/permittivity at the stated frequency, and a branch with Im k>0 into a semi-infinite conductor.
- The good-conductor approximation neglects displacement current relative to conduction. Anomalous skin effect, magnetic dispersion, nonlocal transport or strongly complex frequency-dependent conductivity require their actual constitutive relations; δ is an amplitude depth.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Classical Electromagnetism (2014): Wave propagation in conducting media: Equations 800–809: complex permittivity with exp(−iωt), Ohmic low-frequency response, dispersion, branch and good-conductor skin depth. Relative ε of the source is replaced by absolute ε=ε₀ε_r; keeps μ=μ₀ rather than claiming arbitrary magnetic media.
2026-10-10 · Independent AI editorial review: All 136 unique authored Physics compact statements, all hypotheses and displayed equations/variable/units tables, all 192 Physics-origin semantic links, exact 165 author inspection matrix and mapped retained conceptual claims have been independently read. Three Physics-tagged Measurement realization records are delegated to root Measurement review. Scientific source verification combines exact author section inspection with independent whole compact-content/semantic review and targeted primary rechecks recorded below; it does not claim each full source body was independently reread. Independent AI editorial review is not human specialist certification or experimental replication. Field inventory is approved after independently reviewing the two added source-inspected band-construction methods. Receipt: physics-independent-content-inventory-review.1.
Entry details
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