RayDiagrams - 300 ' CHAPTER 13 V'REFLEC (A) Case 1. r 'I -...

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Unformatted text preview: 300 ' CHAPTER 13 V'REFLEC (A) Case 1. r 'I - case . . Case 1; ' ' ' - reflecte When It the obj: .prinéip: Case flected .never n mirror, 13-19(1 “heated . A co “diagram an iniag seconde the par: flected. produce to meei parallel object 1: mirror, «and 10( principc is move as the C Figure '13-19 Ray diagrams of image formation by concave mirrors. Case 3. Object at the center of curvature. When the object arrow is at the center of curvature, as shown in Figure 13-19(C), the image of the arrowhead is found inverted at C. When the object is at the center of curvature, the image is real, inverted, the same Size as the object, and located atthe center of curvature. Case 4. Object between the center of curvature and principal focus. This case is the converse of Case 2 and is shown in Figure 13-19(D). The image is real, inverted, enlarged, and located beyond the center of curvature. The nearer the object approaches the principal focus of the mirror, the larger the image becomes and the farther it is beyond C. = REFLECTION I 301 Case 5. Object at principal focus. This case is the converse of Case 1; all rays originating from the same point on the object are refleCted from the mirror as parallel rays. 'See Figure 13—19(E). When the object is at the principal focus, no image is formed. If the object is a point source, all reflected rays are parallel to the principal axis. ' ‘ Case 6. Object between principal focus and mirror. The re- fiected rays from any point on the object are divergent; they can never meet to form a real image. They appear to meet behind the mirror, however, to form a virtual image as shown in Figure 13-19(13). In this case, the image is virtual, erect, enlarged, and located behind the mirror. diagram shown in Figure 13420 can be used to show how such an image is formed. The arrow AB represents the object. The secondary axes and the normals at the points of incidence of the parallel rays are radii produced. The parallel rays are re- flected from the surface of the mirror as divergent rays. When produced behind the mirror, the reflected parallel rays appear to meet at the principal focus. The image is formed where parallel and secondary-axis rays emanating from the same object point appear to intersect behind the mirror. In aconvex mirror, all images are virtual, erect, smaller than the object, and located behind the mirror between the vertex and the principal focus. The size of the image increases as the object is moved closer to the mirror, but it can never become as large as the object itself. A convex mirror forms an erect image of reduced size. The 13.1% Images formed by convex mirrors Figare 13-20 The only image formed by a convex mirrorqis virtual, erect, re- duced, and located behind the mirror. .‘3; 4 W,m......-..___.____.s, ‘ Figure 14-21 Ray diagrams of image formation by converging lenses. aEFRAc 322 ' 7 CHAPTER 14 jector, 'used in Case , verse 0 parallel and sea Case The 001 passing Z.~opposin the obj: and [0C1 - magnifi - and tele The ( a diverg Divergi' lens, or -- formati: (E) Case 5. (F) Case 6. 2:... ‘ifih ; A ' ‘ 'Dbiect Case 3. Object at a distance equal to twice the focal length. _ For t] The construction of the image is shown in (C). The image is real, _ rati( inverted, the same size as the object, and loaned at 2F onrthe. . the sam opposite side of the lens. An inverting lens of a field telescope, which inverts an image without changing its size, is an applica- tion of Case 3. Case 4. Object at a distance between one and two focal lengths Where h away. This is the converse of Case 2 and is shown in (D). The ..I_‘especti‘ image is real, inverted, enlarged, and located beyond 2F on the"; The obje opposite side of the lens. The compound microscope, slide pro- The e REFRACTION ' 7 323 jector, and motion picture projector are all applications of a lens uSed in this manner. Case 5. Object at the principal focus. This case is the con- verse of Case 1. No image is formed, since the rays of light are parallel. as they leave the lens (E). The lenses used in lighthouses and searchlights are applications of Case 5. Case 6. Object at a distance less than one focallength away. The construction in (F) showsthat the rays are divergent after passing through the lens and cannot form a real image on the opposite side of the lens. These rays appear to converge behind the object to produce an image that is virtual, erect, enlarged, and located on the same side of the lens as the object. The simple magnifier and the eyepiece lenses of microscopes, binoculars, and telescopes form images as shown in Case 6. The only. kind of image of a real object that can be formed by a diverging lens. is one that is virtual, erect, and reduced in size. Diverging lenses are used to neutralize the effect of a converging lens, or to reduce its converging effect to some extent. The image formation is shown in Figure 14-22. Object - ‘ image For thin lenses, the ratio of object size to image/“size equals the ratio of the object distance to image distance. This rule is the same as the rule for curved mirrors/Thus hi d1 ho do Where no and hi represent the heights of the object and the image 14.1.0 Images formed by diverging lenses Figure 14-22 The image, of an object formed by a diverging lens. 14.11 Object-image relationships respectively, and d0 and di represent the respective distances of observe that the lens equations are the object and image from the optical center of the lens. the same as the mirror equations of The equation used to determine the distances of the object Section 13.12. i i 3. ,1 ...
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This note was uploaded on 07/16/2011 for the course PHY 2005 taught by Professor Lee during the Summer '08 term at University of Florida.

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RayDiagrams - 300 ' CHAPTER 13 V'REFLEC (A) Case 1. r 'I -...

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