# Chapter 23; Mirrors and Lenses

 A Reflection is: When a wave reaches a boundary between two mediums and is turned around Total Reflection reflection boundary with a more rigid medium Partial Reflection reflection boundary with a less rigid medium Plane Mirrors are: Flat mirrors which form a virtual image Plane Mirror Rules - Images same size and orientation- Image left to right- Must be half the height of the object to see entire object Principle Axis Line perpendicular to the mirror; passes through the center of curvature Center of Curvature The geometric center fo the sphere Focal Length 1/2 of the Center of Curvature Image Distance Distance from the mirror to the object Concave Mirror - Outside Focal Length - real image (formed in front of the mirror)- image inverted (always)- image smaller than object- focal length positive Concave Mirror - Inside Focal Length - virtual image (image formed behind mirror)- image upright- image larger than object- focal length positive Convex Mirror - virtual image (formed behind mirror)- image upright- image smaller than object- exchanges field of view for size (larger field; smaller size)- reflective on the outside- focal length negative Any light ray which approaches the mirror parallel to the principle axis will: be reflected through the focal point Any light ray which passes through the focal point will be: reflected parallel to the principle axis Image distances are negative if: the image is virtual Image distances are positive if: the image is real Object distances are always: POSITIVE! Mirror and Lens Equations 1/f = 1/di + 1/dom = hi/ho = -di/do If magnification is positive: the image is upright If magnification is negative: the image is inverted Power Equation for Lenses P = 1/f measured in diopters(1/m); focal lenght MUST be in meters Refraction Equation nosinOi = nsinOr (no - moving out of; n - moving in to)n=(sin i)/(sin r) Snell's Law & the Index of Refraction - how much a light bends at a boundary n=C/vs If you are going out of a substance into air, you use the reciprocal of the n value(C = 3x108 m/s) If you are going from one substance into another, you find the n for the boundary by dividing the n value of what you are going into by the n value of what you are leaving Refraction the bending of light at a boundary; if the speed in the new medium is less than the speed of the old, the wave bends toward the normal line, and vise versa Converging Lens Convex (curve out); make light converge earlier; focal length positive Diverging Lens Concave (curve in); diverge light; focal length negative Spherical Mirror Rules - Real images appear on the same side as object- Virtual images appear behind the mirror- Object distances always positive- Image distance is negative Lens Rules - Real images appear on the opposite side of the object- Virtual images appear on the same side of the lens- Object distances are always positive- Image height positive = upright- Image height negative = inverted- Can only cast real images onto a screen- di = negative if on same side as object; vise versa The Eye - lens focuses image on the retina- image formed in front of retina = nearsighted- image formed behind the retina = farsighted Corrective Lenses - nearsight: too much convergence; use diverging lenses to correct; can only do lasic on nearsighted people - farsight: too much divergance; use converging lens to correct AuthorAnonymous ID15434 Card SetChapter 23; Mirrors and Lenses DescriptionChapter 23 Test Study; Physics Updated2010-04-21T02:12:43Z Show Answers