Update 2022-02-17 08:44
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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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<!-- 2022-02-15 Tue 10:14 -->
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<!-- 2022-02-17 Thu 08:42 -->
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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="org07059aa">
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<div class="main div" id="org19b6c6b">
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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="org07b7c6e">
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<div class="main div" id="orgbcecf63">
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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="org8bacbfc">
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<div class="example div" id="org053a13e">
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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="org533d96e">
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<div class="example div" id="orga6e236b">
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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="orgfda1e99">
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<div class="main div" id="orgf6c2f6b">
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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="orgad54b08">
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<div class="main div" id="org555861c">
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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="org6c12ab4">
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<div class="main div" id="orgad5f974">
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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="org9b58506">
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<div class="example div" id="org83cb9f1">
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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="orgaec5c97">
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<div class="example div" id="org9d43c5a">
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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="org77190da">
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<div class="main div" id="org7d8e5ae">
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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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@@ -2051,7 +2051,7 @@ 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: 2022-02-15 Tue 10:14</p>
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<p class="date">Created: 2022-02-17 Thu 08:42</p>
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<p class="validation"></p>
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</div>
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