138 lines
5.3 KiB
HTML
138 lines
5.3 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>Light and Optics - Refraction - Physics 299</title>
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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" width="189"></h1>
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</center>
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<center>
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<h1>Refraction</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>"Technology...the knack of so arranging
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the world so that we need not experience it"</i></font><br>
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Max Frisch<br>
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</center>
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<img src="netbar.gif" align="middle" height="40" width="100%"> <br>
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<br>
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<ul>
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<li>Refraction may be defined as the <i>"bending"</i> of light
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(or any EM wave) as it passes from one medium to another.
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The bending is caused by differing speeds of the wave in
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the two media.</li>
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<br>
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<li><b>Refractive Index</b><br>
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The refractive index, n, of a medium is defined as the ratio of
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the speed of light in a vacuum to the speed of light in the
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medium<br>
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<br>
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<center><img alt="" src="lo_refraction_eqn1.gif" style="width:
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219px; height: 44px;"><br>
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</center>
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<br>
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</li>
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<li><img src="Snell.jpg" alt="Snell picture" align="left"
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height="109" width="90"> <a
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href="http://www-gap.dcs.st-and.ac.uk/%7Ehistory/Mathematicians/Snell.html">Snell</a>
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<b> 's Law (Law of Refraction)</b>, describes exactly how much
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the light is bent when passing from one medium to another.<br>
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</li>
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</ul>
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<div align="center"><img src="lo_snellslaw.gif" alt="Snells law"
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align="middle" height="101" width="306"> <br clear="all">
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<div align="center"><img src="lo_refracpic.jpg" alt="Refraction
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picture" align="middle" height="300" width="400"> <br>
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<div align="left"><br>
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<ul>
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<li><b>Important points</b></li>
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</ul>
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<b></b>
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<ul>
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<ul>
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<li>Light is bent towards the normal when moving into a
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medium of larger refractive index.</li>
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</ul>
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</ul>
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<ul>
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<ul>
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<li>Angles of incidence, reflection and refraction are all
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measured with respect to the normal. <br>
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</li>
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</ul>
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</ul>
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<ul>
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<ul>
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<li>As a general rule the refractive index increases with
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the density of the medium. For example, the
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refractive index of glass (1.5) is greater than that of
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water (1.33) - glass is more dense than water.</li>
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</ul>
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</ul>
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<ul>
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<ul>
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<li>Light incident normally is not deflected.</li>
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</ul>
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</ul>
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<ul>
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<ul>
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<li>Light rays are <i>"reversible"</i>. In other
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words the refracted ray in the above diagram can act as
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an incident ray and the incident ray will represent the
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direction of the refracted ray.</li>
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</ul>
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</ul>
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<ul>
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<ul>
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<li>The refractive index of a medium depends on the
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wavelength of light, e.g. in glass, blue light travels
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more slowly than red light. This phenomena is
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called "dispersion".<br>
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</li>
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</ul>
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</ul>
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</div>
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</div>
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</div>
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<img src="netbar.gif" height="40" width="100%">
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<center>
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<p style="font-style: italic; color: rgb(255, 0, 0);"
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class="MsoNormal">What is <span style="font-size: 13.5pt;
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color: rgb(0, 0, 0);">π</span>?<br>
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Mathematician: "<span style="font-size: 13.5pt; color: rgb(0, 0,
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0);">π</span><span style="color: rgb(0, 0, 0);"> </span>is
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the ratio of the circumference of a circle to its diameter."<br>
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Engineer: "<span style="font-size: 13.5pt; color: rgb(0, 0, 0);">π</span>
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is about 22/7."<br>
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Physicist: "<span style="font-size: 13.5pt; color: rgb(0, 0,
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0);">π</span> is 3.14159 plus or minus 0.000005."<br>
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Computer Programmer: "<span style="font-size: 13.5pt; color:
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rgb(0, 0, 0);">π</span> is 3.141592653589 in double
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precision."<br>
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Nutritionist: "You one track math-minded fellows, <span
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style="font-size: 13.5pt; color: rgb(0, 0, 0);">Pie</span> is
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a healthy and delicious dessert!"</p>
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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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