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Unformatted text preview: pokharel (pp7242) Optics walther (16180) 1 This print-out should have 33 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points An object, slanted at an angle of 45 , is placed in front of a vertical plane mirror, as shown. Mirror Which of the following shows the appar- ent position and orientation of the objects image? 1. image 2. image 3. image 4. image correct 5. image 6. image 7. image 8. image Explanation: For a plane mirror, the line connecting a point of the object and the corresponding point of the image is perpendicular to the mirror, and corresponding distances from the points to the mirror are the same. Thus, the image should be image object 002 10.0 points An object is placed near a plane mirror, as shown. mirror surface Object M R T G Y Which of the labeled points is the position of the image? 1. T 2. R 3. M 4. Y correct 5. G Explanation: The line connecting the object and its im- pokharel (pp7242) Optics walther (16180) 2 age should be perpendicular to the plane of the mirror, and the perpendicular distance from the image to the mirror is the same as the perpendicular distance from the object to mirror. mirror surface Eye Object M R T G Image Clearly only point Y is the position of the image. 003 10.0 points Hint: A ray diagram would be helpful. Determine the minimum height of a vertical flat mirror in which a person 80 in . in height can see his or her full image. Correct answer: 40 in . . Explanation: In the figure, the mirror is labeled AB . A ray from the womans foot F strikes the bottom of the mirror at B , with an angle equal to and proceeds to the womans eye. L C D A B E T F M The two right triangles EBM and FBM are identical, since they share the common side MB and angle . Therefore EM = MF = 1 2 EF which is also the distance BC . Similarly, a ray from the top of the womans head T strikes the top of the mirror at A and proceeds to her eye. The same line of reasoning as above leads to the conclusion that DA = 1 2 TE Thus the length AB of the mirror is 1 2 ( TE + EF ), which is one half the womans height. Note that the mirrors bottom edge must be exactly 1 2 EF from the floor for a full-height image to be possible. Note also that the conclusions reached here are valid regardless of how far she stands from the mirror. 004 (part 1 of 2) 10.0 points How does the smoothness of a mirror affect the clarity of the image you see? 1. There is no change in the image. 2. The image becomes clear. correct 3. The image becomes blur. Explanation: The smoother the mirror, the clearer the image. 005 (part 2 of 2) 10.0 points What is the difference between a set of parallel rays reflected off a very smooth mirror and the same rays reflected off a more bumpy mirror made of the exact material?...
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This note was uploaded on 06/07/2010 for the course PHYSICS 58930 taught by Professor Kleinman during the Fall '09 term at University of Texas at Austin.
- Fall '09