SWhat changed
Poynting derives a local electromagnetic energy balance from Maxwell’s theory and represents field-energy transport by a cross product of electric and magnetic intensities, illustrating how power reaches circuits and waves.
Scientific scope
Poynting derives a local electromagnetic energy balance from Maxwell’s theory and represents field-energy transport by a cross product of electric and magnetic intensities, illustrating how power reaches circuits and waves. The derivation uses Maxwell’s stated medium-energy and constitutive model; stationary-matter and moving-matter work terms must not be conflated. The original uses historical units and a 1/(4*pi) factor, not verbatim modern SI E cross H. Ohmic wire and slow-discharge examples, thermoelectric assumptions and uniform plane-wave cases have their own restrictions. The cell-potential interpretation is explicitly uncertain, and a proposed dielectric probe is prospective, not a completed experiment. Ideal motor efficiency reaches unity at a zero-power limit, not a practical perpetual-motion result. Conservation fixes a divergence and does not alone certify unique microscopic energy paths. Quantum theory, arbitrary dispersive/nonlinear media and all later power engineering are excluded. The complete derivation and its formulas have not been independently certified here.
Evidence
Source-linked, scoped account of the original work. The published scope states the scientific assumptions and remaining verification limits. WRS has not independently certified the full proof, experimental result or system benchmark.
Contributors
- J. H. Poynting · SCIENCE: Original source-listed scientific author of this scoped work; byline does not determine effort fractions.
Provisional WRS assessment, edition 2026-10-16.1. Independent expert calibration is pending. This grade does not certify correctness or assign ownership.
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