Update 2022-03-15 10:07
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-26
@@ -1,7 +1,7 @@
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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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@@ -1617,7 +1617,6 @@ Table of contents
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Earlier: work done to assemble a static charge distribution:
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\[
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W_e = \frac{\varepsilon_0}{2} \int d\tau ~E^2
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\tag{\ref{eq:Energy_as_int_E2}}
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\]
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Work necessary to get currents going:
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\[
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@@ -1637,14 +1636,14 @@ done by EM forces? From Lorentz force law:
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Really, we're looking at a small volume element \(d\tau\) carrying charge \(\rho d\tau\), moving
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at velocity \({\bf v}\) such that \({\bf J} = \rho {\bf v}\). Thus,
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</p>
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<div class="eqlabel" id="orgc9958b2">
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<div class="eqlabel" id="org935dce9">
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<p>
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<a id="dWdt_intEJ"></a><a href="./emd_ce_poy.html#dWdt_intEJ"><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="orgf9bbccb">
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<div class="alteqlabels" id="orgad7d22c">
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<ul class="org-ul">
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<li>Gr (8.6)</li>
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</ul>
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@@ -1684,18 +1683,18 @@ so we get
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Substituting this in <a href="./emd_ce_poy.html#dWdt_intEJ">dWdt_intEJ</a> and using the divergence theorem,
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we obtain
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</p>
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<div class="main div" id="orgead023b">
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<div class="main div" id="orgdbc3e5c">
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<p>
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<b>Poynting's theorem</b>
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</p>
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<div class="eqlabel" id="org1b1ef48">
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<div class="eqlabel" id="orgc64c555">
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<p>
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<a id="👉Thm"></a><a href="./emd_ce_poy.html#👉Thm"><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="org9c51283">
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<div class="alteqlabels" id="orgf1ac980">
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<ul class="org-ul">
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<li>Gr (8.9)</li>
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</ul>
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@@ -1721,18 +1720,18 @@ energy is carried by EM fields out of \({\cal V}\) across its boundary surface.
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<p>
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Energy per unit time, per unit area carried by EM fields: given by the
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</p>
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<div class="core div" id="orgafa4bdd">
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<div class="core div" id="orga8e7c87">
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<p>
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<b>Poynting vector</b>
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</p>
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<div class="eqlabel" id="org0aaf227">
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<div class="eqlabel" id="org7fb23da">
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<p>
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<a id="PoyntingVec"></a><a href="./emd_ce_poy.html#PoyntingVec"><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="org05edf23">
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<div class="alteqlabels" id="org8150e29">
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<ul class="org-ul">
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<li>Gr (8.10)</li>
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</ul>
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@@ -1751,18 +1750,18 @@ Energy per unit time, per unit area carried by EM fields: given by the
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<p>
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We can thus express Poynting's theorem more compactly:
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</p>
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<div class="core div" id="orgf7b3c73">
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<div class="core div" id="org41e1182">
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<p>
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<b>Poynting's theorem</b> (integral form)
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</p>
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<div class="eqlabel" id="org610ce5e">
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<div class="eqlabel" id="orgfa25d4a">
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<p>
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<a id="PoyntingThm_int"></a><a href="./emd_ce_poy.html#PoyntingThm_int"><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="org462a7a9">
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<div class="alteqlabels" id="org264bb7a">
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<ul class="org-ul">
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<li>Gr (8.11)</li>
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</ul>
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@@ -1781,18 +1780,18 @@ We can thus express Poynting's theorem more compactly:
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<p>
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where we have defined the total
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</p>
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<div class="core div" id="org49394fc">
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<div class="core div" id="orga6dad30">
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<p>
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<b>Energy in electromagnetic fields</b>
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</p>
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<div class="eqlabel" id="org2fd18f3">
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<div class="eqlabel" id="org16b17ef">
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<p>
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<a id="Uem"></a><a href="./emd_ce_poy.html#Uem"><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="orge0e6bd0">
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<div class="alteqlabels" id="orgdf4c40f">
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<ul class="org-ul">
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<li>Gr (8.5)</li>
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</ul>
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@@ -1821,18 +1820,18 @@ Then,
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\]
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so we get the
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</p>
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<div class="core div" id="orgb7f6aa8">
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<div class="core div" id="orgfd64b94">
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<p>
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<b>Poynting theorem</b> (differential form)
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</p>
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<div class="eqlabel" id="orgc43f9ba">
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<div class="eqlabel" id="org47e48c8">
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<p>
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<a id="PoyntingThm"></a><a href="./emd_ce_poy.html#PoyntingThm"><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="org50e67b6">
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<div class="alteqlabels" id="orge4a2af6">
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<ul class="org-ul">
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<li>Gr (8.14)</li>
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</ul>
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@@ -1855,7 +1854,7 @@ and has a similar for to the continuity equation
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<div class="example div" id="org76ab6ea">
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<div class="example div" id="org5f795de">
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<p>
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<b>Example: Joule heating</b>
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</p>
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@@ -1881,7 +1880,7 @@ wire of radius \(a\),
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\]
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Poynting:
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\[
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{\boldsymbol S} = \frac{1}{\mu_0} \frac{V}{L} \frac{\mu_0 I}{2\pi a} \hat{\boldsymbol x} \times \hat{\boldsymbol \varphi} = -\frac{VI}{2\pi a L} \hat{\boldsymbol s}
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{\boldsymbol S} = \frac{1}{\mu_0} \frac{V}{L} \frac{\mu_0 I}{2\pi a} \hat{\boldsymbol x} \times \hat{\boldsymbol \varphi} = -\frac{VI}{2\pi a L} \hat{\boldsymbol r}
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\]
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and points radially inwards. Energy per unit time passing surface of wire:
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\[
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@@ -1912,7 +1911,7 @@ 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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