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Diff — Maxwell's equations

Revision #1399 → #1772 · back to history

modifiedMaxwell's microscopic equations (SI)921b2725eed8
FieldFrom #1399To #1772
anchors[{"section":"Microscopic version in SI units","snippet":"Maxwell's microscopic equations are written as"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{aligned}\\nabla \\cdot \\mathbf {E} \\,\\,\\,&={\\frac {\\rho }{\\varepsilon _{0}}}\\\\\\nabla \\cdot \\mathbf {B} \\,\\,\\,&=0\\\\\\nabla \\times \\mathbf {E} &=-{\\frac {\\partial \\mathbf {B} }{\\partial t}}\\\\\\nabla \\times \\mathbf {B} &=\\mu _{0}\\left(\\mathbf {J} +\\varepsilon _{0}{\\frac {\\partial \\mathbf {E} }{\\partial t}}\\right)\\end{aligned}}}"}]
modifiedDifferentiation under the integral signcb4e9b6f3abb
FieldFrom #1399To #1772
anchors[{"section":"Integral equations","snippet":"we can bring the differentiation under the integral sign in Faraday's law"},{"type":"math_alttext","value":"{\\displaystyle {\\frac {\\mathrm {d} }{\\mathrm {d} t}}\\iint _{\\Sigma }\\mathbf {B} \\cdot \\mathrm {d} \\mathbf {S} =\\iint _{\\Sigma }{\\frac {\\partial \\mathbf {B} }{\\partial t}}\\cdot \\mathrm {d} \\mathbf {S} \\,,}"}]
modifiedTotal enclosed electric chargef0a58f1a15be
FieldFrom #1399To #1772
anchors[{"section":"Integral equations","snippet":"The total electric charge Q enclosed in Ω is the volume integral over Ω of the charge density ρ"},{"type":"math_alttext","value":"{\\displaystyle Q=\\iiint _{\\Omega }\\rho \\ \\mathrm {d} V,}"}]
modifiedNet magnetic flux1db72f1ffef2
FieldFrom #1399To #1772
anchors[{"section":"Integral equations","snippet":"The net magnetic flux Φ B is the surface integral of the magnetic field B passing through a fixed surface"},{"type":"math_alttext","value":"{\\displaystyle \\Phi _{B}=\\iint _{\\Sigma }\\mathbf {B} \\cdot \\mathrm {d} \\mathbf {S} ,}"}]
modifiedNet electric fluxfd866d96b138
FieldFrom #1399To #1772
anchors[{"section":"Integral equations","snippet":"The net electric flux Φ E is the surface integral of the electric field E passing through Σ"},{"type":"math_alttext","value":"{\\displaystyle \\Phi _{E}=\\iint _{\\Sigma }\\mathbf {E} \\cdot \\mathrm {d} \\mathbf {S} ,}"}]
modifiedNet electric current1b8517f33002
FieldFrom #1399To #1772
anchors[{"section":"Integral equations","snippet":"The net electric current I is the surface integral of the electric current density J passing through Σ"},{"type":"math_alttext","value":"{\\displaystyle I=\\iint _{\\Sigma }\\mathbf {J} \\cdot \\mathrm {d} \\mathbf {S} ,}"}]
modifiedEquivalence of differential and integral formsec33fd04a163
FieldFrom #1399To #1772
mathlib.declintegral_divergence_of_hasFDerivAt_off_countableMeasureTheory.integral_divergence_of_hasFDerivAt_off_countable
modifiedDivergence theorem for electric flux1fc9f750a931
FieldFrom #1399To #1772
mathlib.declintegral_divergence_of_hasFDerivAt_off_countableMeasureTheory.integral_divergence_of_hasFDerivAt_off_countable
modifiedIntegral and differential Gauss's law equivalencec249a0bdaf6d
FieldFrom #1399To #1772
anchors[{"section":"Flux and divergence","snippet":"this is satisfied if and only if the integrand is zero everywhere"},{"type":"math_alttext","value":"{\\displaystyle \\iiint _{\\Omega }\\left(\\nabla \\cdot \\mathbf {E} -{\\frac {\\rho }{\\varepsilon _{0}}}\\right)\\,\\mathrm {d} V=0}"}]
modifiedKelvin–Stokes theorem for circulationde940f2fb5a9
FieldFrom #1399To #1772
anchors[{"section":"Circulation and curl","snippet":"By the Kelvin–Stokes theorem we can rewrite the line integrals of the fields around the closed boundary curve ∂Σ"},{"type":"math_alttext","value":"{\\displaystyle \\oint _{\\partial \\Sigma }\\mathbf {B} \\cdot \\mathrm {d} {\\boldsymbol {\\ell }}=\\iint _{\\Sigma }(\\nabla \\times \\mathbf {B} )\\cdot \\mathrm {d} \\mathbf {S} ,}"},{"type":"math_alttext","value":"{\\displaystyle \\iint _{\\Sigma }\\left(\\nabla \\times \\mathbf {B} -\\mu _{0}\\left(\\mathbf {J} +\\varepsilon _{0}{\\frac {\\partial \\mathbf {E} }{\\partial t}}\\right)\\right)\\cdot \\mathrm {d} \\mathbf {S} =0.}"}]
mathlib.declintegral2_divergence_prod_of_hasFDerivAtMeasureTheory.integral2_divergence_prod_of_hasFDerivAt
modifiedCharge conservation (continuity equation)0330f26c132b
FieldFrom #1399To #1772
anchors[{"section":"Charge conservation","snippet":"The invariance of charge can be derived as a corollary of Maxwell's equations"},{"type":"math_alttext","value":"{\\displaystyle 0=\\nabla \\cdot (\\nabla \\times \\mathbf {B} )=\\nabla \\cdot \\left(\\mu _{0}\\left(\\mathbf {J} +\\varepsilon _{0}{\\frac {\\partial \\mathbf {E} }{\\partial t}}\\right)\\right)=\\mu _{0}\\left(\\nabla \\cdot \\mathbf {J} +\\varepsilon _{0}{\\frac {\\partial }{\\partial t}}\\nabla \\cdot \\mathbf {E} \\right)=\\mu _{0}\\left(\\nabla \\cdot \\mathbf {J} +{\\frac {\\partial \\rho }{\\partial t}}\\right)}"},{"type":"math_alttext","value":"{\\displaystyle {\\frac {\\partial \\rho }{\\partial t}}+\\nabla \\cdot \\mathbf {J} =0.}"}]
addedDiv–curl identity (∇·(∇×F) = 0)1d534111e47b
modifiedMaxwell's equations in vacuumd4568b530279
FieldFrom #1399To #1772
anchors[{"section":"Vacuum equations, electromagnetic waves and speed of light","snippet":"such as in vacuum, Maxwell's equations reduce to"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{aligned}\\nabla \\cdot \\mathbf {E} &=0,&\\nabla \\times \\mathbf {E} +{\\frac {\\partial \\mathbf {B} }{\\partial t}}=0,\\\\\\nabla \\cdot \\mathbf {B} &=0,&\\nabla \\times \\mathbf {B} -\\mu _{0}\\varepsilon _{0}{\\frac {\\partial \\mathbf {E} }{\\partial t}}=0.\\end{aligned}}}"}]
addedCurl-of-curl identitybab3b18b36dd
modifiedElectromagnetic wave equation7b222ad1e7e2
FieldFrom #1399To #1772
anchors[{"section":"Vacuum equations, electromagnetic waves and speed of light","snippet":"the equations above have the form of the standard wave equations"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{aligned}{\\frac {1}{c^{2}}}{\\frac {\\partial ^{2}\\mathbf {E} }{\\partial t^{2}}}-\\nabla ^{2}\\mathbf {E} =0,\\\\{\\frac {1}{c^{2}}}{\\frac {\\partial ^{2}\\mathbf {B} }{\\partial t^{2}}}-\\nabla ^{2}\\mathbf {B} =0.\\end{aligned}}}"}]
modifiedPhase velocity in a medium446248623a67
FieldFrom #1399To #1772
anchors[{"section":"Vacuum equations, electromagnetic waves and speed of light","snippet":"In materials with relative permittivity , ε r , and relative permeability , μ r"},{"type":"math_alttext","value":"{\\displaystyle v_{\\text{p}}={\\frac {1}{\\sqrt {\\mu _{0}\\mu _{\\text{r}}\\varepsilon _{0}\\varepsilon _{\\text{r}}}}},}"}]
modifiedSplitting into free and bound parts6f53e040eacd
FieldFrom #1399To #1772
anchors[{"section":"Macroscopic formulation in terms of displacement and magnetizing fields (in matter version)","snippet":"This reflects a splitting of the total electric charge Q and current I"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{aligned}Q&=Q_{\\text{f}}+Q_{\\text{b}}=\\iiint _{\\Omega }\\left(\\rho _{\\text{f}}+\\rho _{\\text{b}}\\right)\\,\\mathrm {d} V=\\iiint _{\\Omega }\\rho \\,\\mathrm {d} V,\\\\I&=I_{\\text{f}}+I_{\\text{b}}=\\iint _{\\Sigma }\\left(\\mathbf {J} _{\\text{f}}+\\mathbf {J} _{\\text{b}}\\right)\\cdot \\mathrm {d} \\mathbf {S} =\\iint _{\\Sigma }\\mathbf {J} \\cdot \\mathrm {d} \\mathbf {S} .\\end{aligned}}}"}]
modifiedAuxiliary fields D and H14a932b282fb
FieldFrom #1399To #1772
anchors[{"section":"Auxiliary fields, polarization and magnetization","snippet":"The definitions of the auxiliary fields are"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{aligned}\\mathbf {D} (\\mathbf {r} ,t)&=\\varepsilon _{0}\\mathbf {E} (\\mathbf {r} ,t)+\\mathbf {P} (\\mathbf {r} ,t),\\\\\\mathbf {H} (\\mathbf {r} ,t)&={\\frac {1}{\\mu _{0}}}\\mathbf {B} (\\mathbf {r} ,t)-\\mathbf {M} (\\mathbf {r} ,t),\\end{aligned}}}"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{aligned}\\rho _{\\text{b}}&=-\\nabla \\cdot \\mathbf {P} ,\\\\\\mathbf {J} _{\\text{b}}&=\\nabla \\times \\mathbf {M} +{\\frac {\\partial \\mathbf {P} }{\\partial t}}.\\end{aligned}}}"}]
modifiedBound charge and current densities5a42c3eb4cee
FieldFrom #1399To #1772
anchors[{"section":"Auxiliary fields, polarization and magnetization","snippet":"The macroscopic bound charge density ρ b and bound current density J b in terms of polarization P and magnetization M are then defined as"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{aligned}\\mathbf {D} (\\mathbf {r} ,t)&=\\varepsilon _{0}\\mathbf {E} (\\mathbf {r} ,t)+\\mathbf {P} (\\mathbf {r} ,t),\\\\\\mathbf {H} (\\mathbf {r} ,t)&={\\frac {1}{\\mu _{0}}}\\mathbf {B} (\\mathbf {r} ,t)-\\mathbf {M} (\\mathbf {r} ,t),\\end{aligned}}}"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{aligned}\\rho _{\\text{b}}&=-\\nabla \\cdot \\mathbf {P} ,\\\\\\mathbf {J} _{\\text{b}}&=\\nabla \\times \\mathbf {M} +{\\frac {\\partial \\mathbf {P} }{\\partial t}}.\\end{aligned}}}"}]
modifiedMacroscopic equations reproduce microscopic03341fdbc73d
FieldFrom #1399To #1772
anchors[{"section":"Auxiliary fields, polarization and magnetization","snippet":"use the defining relations above to eliminate D , and H"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{aligned}\\rho &=\\rho _{\\text{b}}+\\rho _{\\text{f}},\\\\\\mathbf {J} &=\\mathbf {J} _{\\text{b}}+\\mathbf {J} _{\\text{f}},\\end{aligned}}}"}]
modifiedConstitutive relations without polarization/magnetization253999624060
FieldFrom #1399To #1772
anchors[{"section":"Constitutive relations","snippet":"For materials without polarization and magnetization, the constitutive relations are"},{"type":"math_alttext","value":"{\\displaystyle \\mathbf {D} =\\varepsilon _{0}\\mathbf {E} ,\\quad \\mathbf {H} ={\\frac {1}{\\mu _{0}}}\\mathbf {B} ,}"}]
modifiedLinear material constitutive relations928939bf2c7f
FieldFrom #1399To #1772
anchors[{"section":"Constitutive relations","snippet":"for linear materials the constitutive relations are"},{"type":"math_alttext","value":"{\\displaystyle \\mathbf {D} =\\varepsilon \\mathbf {E} ,\\quad \\mathbf {H} ={\\frac {1}{\\mu }}\\mathbf {B} ,}"}]
modifiedOhm's law constitutive relation0e7844615762
FieldFrom #1399To #1772
anchors[{"section":"Constitutive relations","snippet":"included Ohm's law in the form"},{"type":"math_alttext","value":"{\\displaystyle \\mathbf {J} _{\\text{f}}=\\sigma \\mathbf {E} .}"}]
addedMinkowski metric tensor697b80796ceb
addedd'Alembert operatora5395bed9344