125 lines
5.2 KiB
HTML
125 lines
5.2 KiB
HTML
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<!DOCTYPE html PUBLIC "-//w3c//dtd html 4.0 transitional//en">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html;
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charset=windows-1252">
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<meta name="GENERATOR" content="Mozilla/4.7 [en] (X11; U; OSF1 V4.0
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alpha) [Netscape]">
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<meta name="Author" content="C. L. Davis">
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<title>Magnetism - Force on Currents - Physics 299</title>
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<meta content="C. L. Davis" name="author">
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</head>
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<body style="color: rgb(0, 0, 0); background-color: rgb(255, 255,
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255);" alink="#ff0000" link="#0000ee" vlink="#551a8b">
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<center>
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<h1> <img src="ULPhys1.gif" align="texttop" height="50"
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width="189"></h1>
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</center>
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<center>
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<h1>Magnetic Forces on Electric Currents <br>
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</h1>
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</center>
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<center><img src="celticbar.gif" height="22" width="576"><br>
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<br>
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<font color="#ff0000"><i>
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<meta http-equiv="content-type" content="text/html;
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charset=windows-1252">
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</i></font><font color="#ff0000"><i>
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<meta http-equiv="content-type" content="text/html;
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charset=windows-1252">
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</i></font>
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<div class="copy-paste-block"><font color="#ff0000"><i><span
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class="bqQuoteLink">"A</span></i></font><font
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color="#ff0000"><i><span class="bqQuoteLink"> fact is a simple
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statement that everyone believes. It is innocent,
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unless found guilty. A hypothesis is a novel
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suggestion that no one wants to believe. It is
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guilty, until found effective</span></i><span></span>"</font><br>
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</div>
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<font color="#ff0000"><i> </i><font color="#000000">Edward Teller</font></font><br>
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</center>
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<img src="netbar.gif" align="middle" height="40" width="100%">
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<blockquote> </blockquote>
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<ul>
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<li> An electric current is simply a collection of charges moving
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along a wire with velocity <b>v<sub>d</sub> </b>, known as the
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drift velocity. We have already seen that the drift
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velocity and current density are related by</li>
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</ul>
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<div align="center"><img alt="eleccurrent eqn2"
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src="elec_current_eqn2.jpg" height="54" width="126"><br>
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<br>
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<blockquote>
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<div align="left">Considering the magnetic force on a single
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charge (e) we find<br>
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<div align="center"><img alt="magforcecurrent"
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src="mag_force_current_eqn1.jpg" height="51" width="90"><br>
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<br>
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<div align="left">Now the total force on a wire comprised of
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(nAl) charge carriers each with charge e is given by<br>
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<br>
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<div align="center"><img alt="magforcecurrenteqn2"
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src="mag_force_current_eqn2.jpg" height="50"
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width="360"><br>
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<br>
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<div align="left">Defining a vector <b>l </b>along the
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wire in the same direction as <b>J</b> and using |<b>J</b>A|
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= i (electric current) we find for the total force on
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the wire<br>
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<br>
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<div align="center"><img alt="magforcecurrenteqn3"
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src="mag_force_current_eqn3.jpg" height="31"
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width="126"><br>
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<br>
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<img alt="magforcecurrentfig1"
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src="mag_force_current_fig1.jpg" height="283"
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width="275">
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<img
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alt="magforcecurrentfig2"
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src="mag_force_current_fig2.jpg" height="276"
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width="346"><br>
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<br>
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<div align="left"><img alt="exclamation"
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src="exclamation-icon.gif" height="30"
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width="31"> Note that for a given current
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negative and positive charge carriers move in
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opposite directions. This leads to a
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force on the wire in the same direction (see
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above), whether the charge carriers are positive
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or negative.<br>
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</div>
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</div>
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</div>
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</div>
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</div>
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</div>
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</div>
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</blockquote>
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<img src="netbar.gif" height="40" width="100%"></div>
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<center>
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<p style="color: rgb(255, 0, 0); font-style: italic;"
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class="MsoNormal">
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<meta http-equiv="content-type" content="text/html;
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charset=windows-1252">
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</p>
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<font color="#ff0000"><i>When chemists die, they barium.<br>
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</i></font><br>
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<br>
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<img src="celticbar.gif" height="22" width="576"> <br>
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<p><i>Dr. C. L. Davis</i> <br>
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<i>Physics Department</i> <br>
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<i>University of Louisville</i> <br>
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<i>email</i>: <a href="mailto:c.l.davis@louisville.edu">c.l.davis@louisville.edu</a>
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<br>
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</p>
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<p><img src="header-index.gif" height="51" width="92"> </p>
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</center>
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<p><br>
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</p>
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</body>
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</html>
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