Update 2022-03-15 10:07
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<!DOCTYPE html>
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<html lang="en">
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<head>
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<!-- 2022-03-07 Mon 20:38 -->
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<!-- 2022-03-15 Tue 08:10 -->
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<meta charset="utf-8">
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<meta name="viewport" content="width=device-width, initial-scale=1">
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<title>Pre-Quantum Electrodynamics</title>
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@@ -1310,10 +1310,6 @@ Table of contents
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</summary>
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<ul>
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<li>
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<a href="./d_m.html#d_m">Diagnostics: Mathematical Preliminaries</a><span class="headline-id">d.m</span>
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</li>
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<li>
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<a href="./d_ems.html#d_ems">Diagnostics: Electromagnetostatics</a><span class="headline-id">d.ems</span>
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</li>
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@@ -1352,6 +1348,10 @@ Table of contents
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<li>
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<a href="./d_red.html#d_red">Diagnostics: Relativistic Electrodynamics</a><span class="headline-id">d.red</span>
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</li>
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<li>
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<a href="./d_m.html#d_m">Diagnostics: Compendium - Mathematics</a><span class="headline-id">d.m</span>
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</li>
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</ul>
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@@ -1616,13 +1616,12 @@ Table of contents
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<p>
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Maxwell's equations in vacuum:
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</p>
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\begin{align}
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\begin{align*}
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(i)~~ &{\boldsymbol \nabla} \cdot {\bf E} = \frac{\rho}{\varepsilon_0}, \hspace{1cm} &\mbox{Gauss}, \nonumber \\
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(ii)~~ &{\boldsymbol \nabla} \cdot {\bf B} = 0, \hspace{1cm} &\mbox{anonymous} \nonumber \\
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(iii)~~ &{\boldsymbol \nabla} \times {\bf E} = -\frac{\partial {\bf B}}{\partial t}, \hspace{1cm} &\mbox{Faraday}, \nonumber \\
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(iv)~~ &{\boldsymbol \nabla} \times {\bf B} = \mu_0 {\bf J} + \mu_0 \varepsilon_0 \frac{\partial {\bf E}}{\partial t}, \hspace{1cm} &\mbox{Ampère + Maxwell}.
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\label{Gr(7.39)}
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\end{align}
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\end{align*}
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<p>
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are complete as they stand. In presence of matter: more convenient to write sources in terms of
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free charges and currents.
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@@ -1642,25 +1641,25 @@ and magnetization \({\bf M}\) produces bound current density <a href="./emsm_msm
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One new feature in nonstatic case: change in electric polarization involves flow of bound charge
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(call it \({\bf J}_p\)) which must be included in total current.
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Consider a small chunk of polarized material.
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Polarization induces charge density \(\sigma_b = P\) at one end and \(-\sigma_b\) at other. If \(P\)
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Polarization induces charge density \(\sigma_b = P\) at one end and \(-\sigma_b\) at other (refer to <a href="./emsm_esm_po.html#sigmab">sigmab</a>. If \(P\)
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increases a bit, charge increases, giving net current
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\[
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dI = \frac{\partial \sigma_b}{\partial t} da_{\perp} = \frac{\partial P}{\partial t} da_{\perp}.
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\]
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We therefore have the
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</p>
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<div class="core div" id="orgf1835ae">
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<div class="core div" id="orge0518b1">
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<p>
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<b>Polarization current density</b>
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</p>
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<div class="eqlabel" id="orgfad2da8">
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<div class="eqlabel" id="org62db796">
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<p>
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<a id="Jp"></a><a href="./emdm_Me_Mem.html#Jp"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
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<path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
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<path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
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</svg></a>
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</p>
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<div class="alteqlabels" id="orgf15b4cb">
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<div class="alteqlabels" id="orgebf1aab">
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<ul class="org-ul">
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<li>Gr (7.48)</li>
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</ul>
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@@ -1677,14 +1676,14 @@ We therefore have the
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</div>
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<p>
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otherwise simply called the {\bf polarization current}.
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otherwise simply called the <b>polarization current</b>.
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This has nothing to do with the bound current \({\bf J}_b\)
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(the latter is associated to magnetization;
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the polarization current is the result of linear motion of charge when
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polarization changes). We can check consistency with the continuity equation
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associated to the conservation of bound charges:
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</p>
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<aside id="orgadb90c7">
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<aside id="orgfd82638">
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<p>
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Note the unfortunate labelling: it would have been nicer to have \(\rho_b\) be the charge associated to current \({\boldsymbol J}_b\) but this is not the common convention.
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</p>
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@@ -1706,15 +1705,15 @@ Changing magnetization does not lead to analogous accumulation of charge and cur
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In view of this: total charge density can be separated into 2 parts,
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<b>free</b> and <b>bound</b>:
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</p>
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<div class="main div" id="orgbe78924">
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<div class="eqlabel" id="org4679dd8">
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<div class="main div" id="org5bd748a">
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<div class="eqlabel" id="org94dfd02">
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<p>
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<a id="rhofb"></a><a href="./emdm_Me_Mem.html#rhofb"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
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<path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
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<path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
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</svg></a>
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</p>
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<div class="alteqlabels" id="orgb7e7ed8">
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<div class="alteqlabels" id="orgd2d4d1d">
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<ul class="org-ul">
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<li>Gr (7.49)</li>
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</ul>
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@@ -1734,15 +1733,15 @@ In view of this: total charge density can be separated into 2 parts,
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and current can be separated into three parts, <b>free</b>, <b>bound</b> and
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<b>polarization</b>:
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</p>
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<div class="main div" id="org1c506a7">
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<div class="eqlabel" id="orgbf0c17d">
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<div class="main div" id="org7ad8d3b">
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<div class="eqlabel" id="org19a6c97">
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<p>
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<a id="Jfbp"></a><a href="./emdm_Me_Mem.html#Jfbp"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
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<path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
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<path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
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</svg></a>
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</p>
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<div class="alteqlabels" id="org33aea7e">
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<div class="alteqlabels" id="orgac73457">
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<ul class="org-ul">
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<li>Gr (7.50)</li>
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</ul>
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@@ -1768,7 +1767,7 @@ Gauss's law: can be rewritten
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\]
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where (as in static case)
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</p>
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<div class="core div" id="org501f375">
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<div class="core div" id="org65ac5cc">
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<p>
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\[
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{\bf D} \equiv \varepsilon_0 {\bf E} + {\bf P}
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@@ -1789,7 +1788,7 @@ or
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\]
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where as before
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</p>
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<div class="core div" id="orgfaac9ca">
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<div class="core div" id="org7e8e1b5">
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<p>
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\[
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{\bf H} \equiv \frac{1}{\mu_0} {\bf B} - {\bf M}
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@@ -1807,18 +1806,18 @@ bound parts, since they don't involve \(\rho\) or \({\bf J}\).
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<p>
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In terms of free charges and currents, we thus get
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</p>
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<div class="core div" id="org4a1df55">
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<div class="core div" id="org089bb13">
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<p>
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<b>Maxwell's equations</b> <i>(in matter)</i>
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</p>
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<div class="eqlabel" id="orga6eb31a">
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<div class="eqlabel" id="orgfabaa36">
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<p>
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<a id="Max_mat"></a><a href="./emdm_Me_Mem.html#Max_mat"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
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<path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
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<path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
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</svg></a>
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</p>
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<div class="alteqlabels" id="org154a0ec">
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<div class="alteqlabels" id="orgaba63f2">
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<ul class="org-ul">
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<li>Gr (7.55)</li>
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</ul>
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@@ -1848,15 +1847,15 @@ This must all be complemented by the <b>constitutive relations</b> giving \({\bf
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in terms of \({\bf E}\) and \({\bf B}\).
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For the restricted case of linear media:
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</p>
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<div class="main div" id="orge60b08f">
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<div class="eqlabel" id="org88284f8">
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<div class="main div" id="org435d93d">
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<div class="eqlabel" id="orgb5db623">
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<p>
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<a id="consrel"></a><a href="./emdm_Me_Mem.html#consrel"><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-link" viewBox="0 0 16 16">
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<path d="M6.354 5.5H4a3 3 0 0 0 0 6h3a3 3 0 0 0 2.83-4H9c-.086 0-.17.01-.25.031A2 2 0 0 1 7 10.5H4a2 2 0 1 1 0-4h1.535c.218-.376.495-.714.82-1z"/>
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<path d="M9 5.5a3 3 0 0 0-2.83 4h1.098A2 2 0 0 1 9 6.5h3a2 2 0 1 1 0 4h-1.535a4.02 4.02 0 0 1-.82 1H12a3 3 0 1 0 0-6H9z"/>
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</svg></a>
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</p>
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<div class="alteqlabels" id="org21479eb">
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<div class="alteqlabels" id="org6a8a0ba">
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<ul class="org-ul">
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<li>Gr (7.56,7.57)</li>
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</ul>
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@@ -1899,7 +1898,7 @@ target="_blank">Creative Commons Attribution 4.0 International License</a>.
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</div>
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<div id="postamble" class="status">
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<p class="author">Author: Jean-Sébastien Caux</p>
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<p class="date">Created: 2022-03-07 Mon 20:38</p>
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<p class="date">Created: 2022-03-15 Tue 08:10</p>
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<p class="validation"></p>
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</div>
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