Electrodynamics of Free- and Bound-Charge Electricity Generators Using Impressed Sources

The conversion of external energy into electricity is the foundation power station and harvesting operation. source supplies an impressed force per unit charge to free or bound produces AC electricity. We analyze electrodynamics ideal generators through a time dependent permanent polarization without any applied electric field, which modifies constitutive relations essential oscillate in lossless way. For both cases, we show that Maxwell's equations, particular Faraday's law are modified, along with required boundary conditions addition effective magnetic current source. case, highlight example electromagnetic generator based on Lorentz force, where polarizes conductor comes from mechanical motion velocity relative stationary DC field. idealized permanently polarized bar electret polarization, underlying principle behind piezoelectric nano-generators. In open circuit state, equivalent Hertzian dipoles, voltage equal induced emf. Analyzing short responses, has capacitive impedance. contrast, for generator, back emf inductance loop defines circuit, directly cancels emf, so across inductor solely determined by Thus, determine topological invariant best describes output generator.