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Reflection and Mirrors

Reflection and Mirrors. Chapter 17 Physics Principles and Problems Zitzewitz, Elliot, Haase, Harper, Herzog, Nelson, Nelson, Schuler and Zorn McGraw Hill, 2005. Law of Reflection. The normal is the imaginary line that is draw perpendicular to the reflective surface.

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Reflection and Mirrors

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  1. Reflection and Mirrors Chapter 17 Physics Principles and Problems Zitzewitz, Elliot, Haase, Harper, Herzog, Nelson, Nelson, Schuler and Zorn McGraw Hill, 2005

  2. Law of Reflection • The normal is the imaginary line that is draw perpendicular to the reflective surface. • The angle between a reflected ray and the normal is equal to the angle between the incident ray and the normal (r = i). http://www.etsu.edu/math/gardner/einstein/e-reflection.jpg http://spaceguard.iasf-roma.inaf.it/tumblingstone/issues/num8/light/img/reflection.gif

  3. Smooth surfaces produce specular reflection (parallel light rays are reflected in parallel). • Rough surfaces produce diffuse reflection (parallel light rays are reflected in non parallel ways). • Individual rays, however, in both cases still adhere to the laws of reflection. http://www.lightandmatter.com/html_books/5op/ch01/figs/specular-and-diffuse-reflection.png http://micro.magnet.fsu.edu/optics/lightandcolor/images/reflectionfigure2.jpg

  4. Plane-Mirror Images • Object is the source of light rays that are to be reflected (could be either luminous like a light-bulb, or illuminated like the rook). • Light travels from object point to the mirror and is reflected. The brain processes this as if the light traveled in a straight path (thus creating a virtual image). http://sol.sci.uop.edu/%7Ejfalward/reflection/castlemirror.jpg

  5. Plane Mirror Image Position and Height • The virtual image position is equal to the negative of the object position. The negative indicates that the image is virtual (di = -do). • The virtual image height is equal to the object height (hi= ho). http://www.physics.brocku.ca/Courses/1P22_Crandles/images/f25007.jpg

  6. Concave Mirrors • Edges of mirror curve towards observer. • C = geometric center of sphere. • CP = line segment between C and P. Also equal to sphere’s radius (r). • P = center of mirror where principle axis intersects the mirror. • F = focal point where reflected parallel rays converge. • f = is the position of the focal point with respect to the mirror (f = r/2). http://www.vidyavahini.ernet.in/shishya/products/AcademicContent/CBSE/X/Physics/light/xlight_files/image001.gif

  7. The properties of an object’s real image (image that is formed from the convergence of light rays) are dependent upon the distance the object is from the concave mirror. http://electron9.phys.utk.edu/optics421/modules/m1/images/concavreal.gif

  8. (a) If the object is more than twice the focal length, than the real image will be inverted and smaller. • (b) If the object is twice the focal length, than the real image will be inverted. • (c) If the object is less than twice the focal length, than the real image will be inverted and bigger. • (d) If the object is the exact focal length that no real image will be seen. • (e) If the object is less than the focal length a virtual image that is larger and upright is formed behind the mirror. http://media.wiley.com/Lux/26/10326.nfg014.jpg

  9. What do these two different pictures of concave mirrors tell you about the object’s position? http://doflick.com/flash/thumbnails//University/Physi cs/REFLECTIONS_FROM_A_CONCAVE_MIRROR.jpg http://www.monticello.org/gallery/innovations/concavemirror.jpg

  10. These properties can be solved for using two different equations. • Mirror Equation - the reciprocal of the focal length of a spherical mirror is equal to the sum of the reciprocals of the image position and the object position. • 1 / f = 1 / di + 1 / do • Magnification - the magnification of an object by a spherical mirror can be calculated by image height divided by the object height (which is equal to the negative of the image position divided by the object position). • m = hi/ ho = -di/ do

  11. Convex Mirrors • Edges of reflective surface curve away from the observer. • Focal point and center of sphere are behind the mirror. • Object reflects a virtual image that is reduced in size. http://electron9.phys.utk.edu/optics421/modules/m1/images/convex.gif

  12. http://4blackbird.com/images/black.jpg

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