Update 2022-02-10 08:34
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@@ -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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<!-- 2022-02-09 Wed 22:40 -->
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<!-- 2022-02-10 Thu 08:32 -->
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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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@@ -1605,7 +1605,7 @@ Table of contents
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<p>
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For many substances: polarization is proportional to field, if the latter isn't too strong:
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</p>
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<div class="main div" id="orga3278d6">
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<div class="main div" id="org6ac9560">
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<p>
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\[
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{\bf P} = \varepsilon_0 \chi_e {\bf E}
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@@ -1635,7 +1635,7 @@ In linear dielectrics:
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\]
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so
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</p>
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<div class="main div" id="org78784fd">
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<div class="main div" id="orgd8cb3ab">
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<p>
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\[
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{\bf D} = \varepsilon {\bf E}
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@@ -1657,7 +1657,7 @@ This is all just nomenclature, everything is already in \ref{Gr(4.30)}.
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<div class="example div" id="org85c03d5">
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<div class="example div" id="org29b4ca7">
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<p>
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\paragraph{Example 4.5:} metal sphere of radius \(a\) carrying charge \(Q\), surrounded out to radius \(b\) by
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a linear dielectric material of permittivity \(\varepsilon\). Find potential at center (relative to infinity).
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@@ -1713,7 +1713,7 @@ of {\it e.g.} \({\bf P}\) would not vanish.
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Only case where parallel works: space entirely filled with homogeneous linear dielectric.
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</p>
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<div class="example div" id="orgc0d8c4c">
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<div class="example div" id="orgd710a3a">
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<p>
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\paragraph{Example 4.6:} parallel-plate capacitor filled with insulating material of
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dielectric constant \(\varepsilon_r\). What is the effect on the capacitance ?
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@@ -1748,7 +1748,7 @@ If \(\rho = 0\), any net charge is on surface, potential then obeys Laplace.
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<p>
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Convenient to rewrite boundary conditions in terms of free charge: from \ref{Gr(4.26)},
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</p>
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<div class="main div" id="org738acac">
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<div class="main div" id="org78d2d1f">
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<p>
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\[
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\varepsilon_{above} E^{\perp}_{above} - \varepsilon_{below} E^{\perp}_{below} = \sigma_f
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@@ -1760,7 +1760,7 @@ Convenient to rewrite boundary conditions in terms of free charge: from \ref{Gr
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<p>
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or in terms of the potential,
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</p>
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<div class="main div" id="org6a5bb81">
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<div class="main div" id="orgc1815c1">
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<p>
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\[
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\varepsilon_{above} \frac{\partial V_{above}}{\partial n} -
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@@ -1773,7 +1773,7 @@ or in terms of the potential,
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<p>
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Potential itself is continuous,
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</p>
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<div class="main div" id="org00bd1e4">
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<div class="main div" id="orgdda22c8">
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<p>
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\[
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V_{above} = V_{below}
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@@ -1785,7 +1785,7 @@ Potential itself is continuous,
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<div class="example div" id="orgf22ddc4">
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<div class="example div" id="org6d6fcc0">
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<p>
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\paragraph{Example 4.7:} sphere of homogeneous dielectric material in uniform electric field \({\bf E}_0\).
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Find electric field inside sphere.
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@@ -1843,7 +1843,7 @@ Thus,
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<div class="example div" id="org3d34c22">
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<div class="example div" id="org1f1cffb">
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<p>
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\paragraph{Example 4.8:} suppose region below \(z = 0\) is filled with uniform linear dielectric with susceptibility \(\chi_e\).
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Calculate force on point charge \(q\) situated a distance \(d\) above origin.
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@@ -1947,7 +1947,7 @@ Special case of linear isotropic dielectric: \({\bf D} = \varepsilon {\bf E}\),
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\]
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Total work done:
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</p>
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<div class="main div" id="org4c9c303">
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<div class="main div" id="orgafaaf7a">
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<p>
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\[
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W = \frac{1}{2} \int d\tau {\bf D} \cdot {\bf E}
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@@ -2049,7 +2049,7 @@ 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: 2022-02-09 Wed 22:40</p>
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<p class="date">Created: 2022-02-10 Thu 08:32</p>
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<p class="validation"></p>
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</div>
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