131 lines
5.0 KiB
HTML
131 lines
5.0 KiB
HTML
<!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"
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content="text/html; charset=ISO-8859-1">
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<meta name="GENERATOR"
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content="Mozilla/4.7 [en] (X11; U; OSF1 V4.0 alpha) [Netscape]">
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<meta name="Author" content="C. L. Davis">
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<title>Light and Optics - Reflection - Physics 299</title>
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</head>
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<body style="color: rgb(0, 0, 0); background-color: rgb(255, 255, 255);"
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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>Reflection</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>"We believe a scientist because he can
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substantiate his remarks, not because he is eloquent and forcible in
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his enunciation. In
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fact we distrust him when he seems to be influencing us by his manner"</i></font><br>
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I. A Richards<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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<div align="center"><img src="lo_reflpic.jpg" alt="reflection picture"
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align="middle" height="314" width="398"> <br>
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<i><a
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href="http://www.3d-dali.com/Artist-Biographies/Edouard_Manet.html">Edouard
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Manet</a> - A bar at the Folies_Bergere</i><br>
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<small>Spot the deliberate(?) mistakes</small><br>
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</div>
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<ul>
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<li>A general description of the reflection of electromagnetic waves
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is obtained by considering the wave nature of the radiation.
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However, when the wavelength of the radiation is small compared
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to any apertures or obstacles nearby we may treat the wave as a stream
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of <i>"particles"</i> traveling in a straight line. This is the
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situation when considering the formation of images by visible light in
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mirrors and lenses. In this case the straight lines
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in which the visible light waves travel are known as <b><i> light rays</i></b>
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. The study of the behaviour of light under these conditons
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is known as Geometric Optics.</li>
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<br>
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<li>Light rays undergo one of two types of reflection -
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diffuse or specular.<br>
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<br>
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<ul>
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<li>Diffuse reflection is more common for almost all objects.
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The reflected light is emitted in all directions due to
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irregularities on the surface of the material.</li>
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<li>Specular reflection occurs if the irregularities of the
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surface are small compared to the wavelength of the light. In
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this case reflection occurs at a single angle, for example from the
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surface of a plane mirror or water.</li>
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</ul>
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<div align="center"><img src="lo_speculardiffuse.jpg"
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alt="specular /diffuse refelction" align="middle" height="194"
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width="465"> <br>
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</div>
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We will consider only specular reflection in
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this course<br>
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</li>
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<br>
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<li><u><b>The law of reflection</b>.</u>(which can be derived from
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Maxwell's equations)<br>
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<br>
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<div align="center"> Angle of incidence = angle of reflection </div>
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<br>
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Angles are measured with respect to the normal to the surface.</li>
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<div align="center"><img src="lo_refl1.gif" alt="reflection1"
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align="middle" height="86" width="161">
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<img src="lo_anim_refl2.gif" alt="reflection2" align="middle"
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height="308" width="223"> <br>
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</div>
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<li><u><b>Ray Tracing and Image Formation in a plane mirror</b></u><br>
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<br>
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Light rays are reflected from a plane mirror according to
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the law of reflection. An image is formed on the "other" side of the
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mirror, where the reflected rays <i>appear</i> to originate.</li>
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</ul>
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<div align="center"><img src="lo_refl4.gif"
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alt="reflection from plane mirror" align="middle" height="299"
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width="324"> </div>
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<ul>
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<br>
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<li> Images formed in plane mirrors have the
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following properties,<br>
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<br>
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<ul>
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<li>Located the same distance behind the mirror as the object is
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in front of the mirror.</li>
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<li>Same size as the object.</li>
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<li>Right and left inversion<br>
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</li>
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<li>Upright</li>
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<li><b>Virtual</b></li>
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</ul>
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<br>
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An image is <b>virtual</b> if light rays do not physically pass
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through it. Real images are formed if light rays actually pass
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through the image. </li>
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</ul>
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<img src="netbar.gif" height="40" width="100%">
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<center><br>
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<span style="font-style: italic; color: rgb(255, 0, 0);">"The
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tides are a fight between the Earth and Moon. All water tends
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towards the moon, because there is no water in the moon, and nature
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abhors a
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vacuum. I forget where the sun joins in this fight."</span><br>
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Middle School Science Test Answer<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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