How statement and proof provenance work
The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.
- Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
- AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
- AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.
These labels describe origin, not correctness: citations and verification chips remain separate evidence.
The image-method certificate for a point charge above a grounded plane
The ideal electrostatic problem of a point charge held above an infinite grounded conducting plane, read in the framework's SI conventions: on the vacuum half-space the image potential is harmonic off the source, has the point-charge distributional source, vanishes on the plane, decays like |x|^-2, and is unique in the stated continuous-boundary and decay class; the plane's induced density is the idealization's bookkeeping normal-derivative reading. The item asserts no finite-plane edge effects, no conductor thickness, no dynamics, no self-force and no measurement, and the half-space conductor and noncompact sheet are explicitly outside the bounded-conductor model and the declared source types. The induced density is explicitly smooth on the whole plane, has absolutely convergent total charge , and the full-space point-plus-plane divergence identity is verified with local tests as a separate mathematical idealization. Matching singularities allow any remainder of order .
Statement
Assume the Axiom of Countable Choice () inherited from the Newtonian, polar and distribution interfaces (The Axiom of Countable Choice ()). Let
Here is the third coordinate unit vector, carries metres, and the coordinates are SI numerical readings in the named frame. Let be a charge parameter (coulombs) and the framework constant (Framework-local SI units, the vacuum constants and the exact/measured status of their values). Define, with arbitrary values on the exceptional sets,
The map is a spatial field of The electric and magnetic fields as fixed-time spatial vector fields in the fixed-time reading, with the units of Framework-local SI units, the vacuum constants and the exact/measured status of their values. Then:
(a) [Candidate field] and pointwise on : the first term is the Coulomb potential of , whose fundamental solution is harmonic off its pole (The Laplace fundamental solution is harmonic off its pole, The localized Newtonian potential and the ideal point-charge Coulomb field(d)), and the second term is and harmonic on the whole of because its pole lies outside ; is on .
(b) [Distributional point source] and
where is the regular distribution of (Regular distribution from a locally integrable function, Locally integrable functions embed in distributions) and the Dirac distribution at (Dirac delta and its derivatives); moreover the field satisfies and in , where the divergence and curl of are the distributional derivatives of its components (Distributional derivative). Thus is a pure electrostatic model on with the fixed-time point source , the static reading of the stationary point charge of Distributional Maxwell equations with point and stationary-sheet sources(b) (The static and pure electrostatic regimes and their fixed-time reading(e)).
(c) [Boundary trace and decay] extends continuously to with on (the two denominators are equal there), and for the cancellation bound holds:
The bound follows by applying the mean value theorem along the segment from to to the function , whose gradient is bounded by there (The mean value theorem, as the case of Cauchy's: for continuous on with and differentiable on there is with , The chain rule for total derivatives: , Continuity and derivatives of positive-base real powers, For a natural the function is differentiable everywhere with derivative ; for it is the constant , with derivative ; for a natural the function is differentiable at every with derivative ; consequently every polynomial function is differentiable at every real, with the derivative computed term by term, The Euclidean inner product on ). In particular as in .
(d) [Uniqueness in the declared class] let be and harmonic on , continuous on , with on , as and as in . Then on . Equivalently, the Dirichlet problem on , on , with the leading singularity of the point charge at and decay at infinity, has exactly one solution in the stated class.
(e) [Physics reading: ideal grounded plane in the fixed-time reading of Laboratory geometry: a restricted inertial chart, its spatial slices and fixed-time fields] the ideal grounded conducting half-space with the field on , below and the induced density (using the normal from the conductor into the vacuum; ) is a model of the same equilibrium structure as The ideal electrostatic conductor model: it is a pure electrostatic field on with the point source at and the equipotential boundary condition on ; the pair satisfies the static electrostatic equations with source on , and the induced density is explicitly , is absolutely integrable over the plane, and has total charge . However, the half-space conductor is not a compact conductor body: the plane is not a compact embedded hypersurface, and are not among the geometric objects of The ideal electrostatic conductor model, the density is not a declared stationary-sheet source of Distributional Maxwell equations with point and stationary-sheet sources(c), and the noncompact plane pairing is not an adopted compact-sheet source of that definition. As a separately specified mathematical idealization, extending by zero below the plane gives and on , where . This verified identity does not extend the framework postulate to arbitrary noncompact sheets. The clause is the explicitly declared idealization whose exact mathematical content is (a)-(d).
(f) [Scope] the statement concerns the ideal point charge above an ideal grounded plane in the declared decay class; it excludes finite-plane edge effects, conductor thickness, transients, moving charges, radiation, self-force and any measurement; no uniqueness is asserted outside the class of (d), and the point-source singularity is never evaluated.
Facts & Assumptions
Given: The half-space , the plane , the point , , the charge parameter , the constant , and the candidate and field of the statement.
The fundamental solution is , smooth and harmonic on ; the Coulomb point-charge branch of The localized Newtonian potential and the ideal point-charge Coulomb field(d) identifies the point-charge potential as locally integrable with distributional Laplacian on and field satisfying , in (The Laplace fundamental solution is harmonic off its pole, The localized Newtonian potential and the ideal point-charge Coulomb field, The Laplacian of a function and of a vector field, Dirac delta and its derivatives).
A function on an open set represents its regular distribution and its distributional first derivatives are the regular distributions of its classical derivatives; distributional differentiation is linear and the Laplacian of a classical harmonic function therefore represents the zero distribution (Regular distribution from a locally integrable function, Locally integrable functions embed in distributions, Distributional derivative, Distribution, Local finite order characterization of distributions, If are differentiable on with integrable, then , Distributional differentiation is continuous and commutes, Test function space d of an open set).
Local integrability in dimension three: the radial integral of over a ball is finite by polar coordinates, finite sums and scalar multiples of locally integrable measurable functions are locally integrable, as are their products with locally bounded measurable functions, and continuous functions are Borel measurable (Polar coordinates decompose Lebesgue measure into r^{n-1} dr d sigma, The polar surface set function on the unit sphere, Integral over a measurable subset, Monotonicity and nonnegative homogeneity of the nonnegative integral, Continuous functions on Euclidean spaces are Borel measurable, Agreement with the existing polar sphere measure, The closed form for the volume of the unit -ball).
Mean value theorem and derivative calculus: for with fixed, is off and , so ; differentiation with respect to instead gives ; the mean value theorem bounds by on the segment (The mean value theorem, as the case of Cauchy's: for continuous on with and differentiable on there is with , The chain rule for total derivatives: , Continuity and derivatives of positive-base real powers, For a natural the function is differentiable everywhere with derivative ; for it is the constant , with derivative ; for a natural the function is differentiable at every with derivative ; consequently every polynomial function is differentiable at every real, with the derivative computed term by term, Directional derivatives and partial derivatives of a map , Sums, scalar multiples, products and quotients: , , , and when , The Euclidean inner product on , The finite and reverse triangle inequalities for a norm; and for every norm on satisfies and is Lipschitz, hence continuous, for , Euclidean maps and diffeomorphisms).
The half-space uniqueness lemma: a function continuous on , and harmonic on , zero on , sub-Coulomb at and vanishing at infinity in is identically zero (Uniqueness for harmonic functions on a punctured half-space with zero trace, decaying at the pole and at infinity).
The polar/Fubini calculus on the plane: integrals over may be computed in polar coordinates, the product and Euclidean measures agree on Borel sets, the plane is Lebesgue null in , and the one-dimensional fundamental theorem computes the radial primitive (Polar coordinates decompose Lebesgue measure into r^{n-1} dr d sigma, Fubini's theorem for L^1 functions on a sigma-finite product, The Borel product of R^m and R^n is the Borel sigma-algebra of R^{m+n}, On Borel subsets of R^{m+n}, the product lambda_m times lambda_n agrees with lambda_{m+n}, A box with a degenerate side is Lebesgue null, and so is every coordinate hyperplane in , The second fundamental theorem: if is differentiable on with and is integrable, then , Riemann–Lebesgue comparison for distribution test integrands, Monotone convergence for the integral).
Framework readings: the fixed-time reading of the pure electrostatic regime identifies the static fields and the stationary point charge of Distributional Maxwell equations with point and stationary-sheet sources(b) with ; the units are those of Framework-local SI units, the vacuum constants and the exact/measured status of their values; and the adopted distributional equations are those of Distributional vacuum Maxwell equations for the declared point and stationary-sheet sources (The static and pure electrostatic regimes and their fixed-time reading(e), The electric and magnetic fields as fixed-time spatial vector fields, Laboratory geometry: a restricted inertial chart, its spatial slices and fixed-time fields, Distributional Maxwell equations with point and stationary-sheet sources).
For there is a smooth function equal to one on and supported strictly inside (Compactly supported scaled Euclidean bumps).
Proof
Clause (a). Write [F1]. The first term is smooth and harmonic off its pole ; the second has its pole at , which lies outside the closed half-space , so it is on and harmonic there by [F1] and linearity of the Laplacian [F2]; hence , there, and is on .
Local integrability and distributional identities. is locally integrable on : is locally integrable in dimension three and is continuous on , and sums and scalar multiples of locally integrable measurable functions are locally integrable [F3]. Its regular distribution is [F2, F3]. On the second term is with classically vanishing Laplacian, so its distributional Laplacian is the regular distribution of the zero function [F2]; the first term has on , hence on the open subset [F1]. Summing gives in . For the field, where is smooth on with , there [F2]; componentwise on by the same representation and [F2], so the distributional divergence and curl of are those of the sum, giving and in [F1, F2]. This is (b); taking it together with [F7] reads as the pure electrostatic model on with the fixed-time point source , as asserted.
Clause (c). On one has for every with , so the bracket in vanishes and extends continuously (indeed away from ) with value on . For the decay, fix with and apply the mean value theorem to on the segment from to : since every point of that segment satisfies , one has and therefore [F4]. Multiplying by gives because for . This is (c).
Clause (d). Let be as in the statement and put on . Then is and harmonic on and continuous on by (a) [step 1.1]; on because both functions vanish there [step 1.3]; as by the assumed leading-singularity condition; and as in because both and do. By [F5] applied to , on , so . This is (d).
Clause (e), first part. On the plane, and ; differentiating the two Coulomb terms, whose gradients are [F4], at gives and , so and hence , a smooth bounded function; the boundary condition on is the equipotential (zero) trace of the ideal grounded plane, and satisfies the static equations with source on by (b) [step 1.2]. The total induced charge is with the polar-coordinate computation and the improper radial primitive justified by [F6]; the identical polar computation with in place of gives , including .
Clause (e), extension identity. Extend by zero to , obtaining by the point-field integrability in [F1] and smoothness away from . The plane pairing is a distribution: on tests supported in a compact box its absolute value is bounded by times the finite area of the box's planar section times . Choose and from [F8], so near and its support lies in . Split an arbitrary scalar test as , . For the half-space identities of step 1.2 give the divergence pairing and zero curl pairing; its plane trace is zero. For , all field/test products are smooth away from the pole and absolutely integrable on a compact box. Fubini and one-dimensional integration by parts [F2, F6] therefore give, for every , . Horizontal boundary terms vanish by compact support; the vertical integral over has precisely the displayed lower-end term. Summing gives only , since away from . Taking the antisymmetric derivative combinations gives the sheet term , because the smooth zero plane trace of has zero horizontal derivatives; the classical curl also vanishes away from by step 1.2. Adding the two test pieces gives and in . No limit at infinity or unproved divergence theorem on a cornered truncation is used.
Scope. The computations above concern exactly the ideal point charge above the ideal grounded plane in the declared class: the plane is not a compact embedded hypersurface and , and the plane pairing are not among the declared conductor or compact stationary-sheet objects of The ideal electrostatic conductor model and Distributional Maxwell equations with point and stationary-sheet sources(c) [F7]; the extension identity of [step 3.1] is a verified statement about the idealization and does not extend the framework postulate to arbitrary noncompact sheets. No finite-plane edge effect, conductor thickness, transient, moving charge, radiation, self-force or measurement is asserted, the singularity at is never evaluated, and uniqueness is claimed only in the class of (d) [step 2.1]. This is (f).
Depends on
The localized Newtonian potential and the ideal point-charge Coulomb field
The ideal electrostatic conductor model
The static and pure electrostatic regimes and their fixed-time reading
The electric and magnetic fields as fixed-time spatial vector fields
Framework-local SI units, the vacuum constants and the exact/measured status of their values
Distributional Maxwell equations with point and stationary-sheet sources
Laboratory geometry: a restricted inertial chart, its spatial slices and fixed-time fields
Uniqueness for harmonic functions on a punctured half-space with zero trace, decaying at the pole and at infinity
The Laplace fundamental solution is harmonic off its pole
If are differentiable on with integrable, then
The mean value theorem, as the case of Cauchy's: for continuous on with and differentiable on there is with
The Laplacian of a function and of a vector field
Directional derivatives and partial derivatives of a map
The chain rule for total derivatives:
Continuity and derivatives of positive-base real powers
For a natural the function is differentiable everywhere with derivative ; for it is the constant , with derivative ; for a natural the function is differentiable at every with derivative ; consequently every polynomial function is differentiable at every real, with the derivative computed term by term
Sums, scalar multiples, products and quotients: , , , and when
Euclidean maps and diffeomorphisms
The Euclidean inner product on
The finite and reverse triangle inequalities for a norm; and for every norm on satisfies and is Lipschitz, hence continuous, for
Distribution
Distributional derivative
Regular distribution from a locally integrable function
Locally integrable functions embed in distributions
Test function space d of an open set
Dirac delta and its derivatives
Monotonicity and nonnegative homogeneity of the nonnegative integral
Continuous functions on Euclidean spaces are Borel measurable
Integral over a measurable subset
The Axiom of Countable Choice ()
Distributional differentiation is continuous and commutes
Polar coordinates decompose Lebesgue measure into r^{n-1} dr d sigma
The polar surface set function on the unit sphere
Agreement with the existing polar sphere measure
The closed form for the volume of the unit -ball
The second fundamental theorem: if is differentiable on with and is integrable, then
Riemann–Lebesgue comparison for distribution test integrands
Monotone convergence for the integral
Fubini's theorem for L^1 functions on a sigma-finite product
The Borel product of R^m and R^n is the Borel sigma-algebra of R^{m+n}
On Borel subsets of R^{m+n}, the product lambda_m times lambda_n agrees with lambda_{m+n}
A box with a degenerate side is Lebesgue null, and so is every coordinate hyperplane in
Distributional vacuum Maxwell equations for the declared point and stationary-sheet sources
Compactly supported scaled Euclidean bumps
Local finite order characterization of distributions
Dependency tree · 2 levels
Sources
- David J. Griffiths, Introduction to Electrodynamics, 3rd edition (Prentice Hall 1999, 596 pp.; full scanned text)
- David Tong, Electromagnetism, University of Cambridge Mathematical Tripos lecture notes (Lent Term 2015, 236 PDF pages)
- Weng Cho Chew, Lectures on Electromagnetic Field Theory (Purdue University, Fall 2020, 497 pp.)