# Ch 23 vocab

 Ray model A model that assumes light travels in rays Ray Straight-line path Geometric optics The subject of light acting as a ray with reflection, refraction, and the formation of images by mirrors and lenses Angle of incidence The angle an incident ray makes with the normal (perpendicular) to the surface Angle of reflection The angle the reflected ray makes with the normal Law of reflection The angle of reflection equals the angle of incidence Diffuse reflection When light hits a rough surface and is reflected in many directions Specular reflection When light hits a smooth surface and reflects in one direction Image Picture made by reflected light Virtual image An optical image formed by the apparent divergence of rays from a point, rather than their actual divergence from a point (when it doesn't actually focus, but our brain connects the dots) Real image An optical image formed by the actual divergence of rays from a point (never upright - opposite of virtual) Convex Spherical mirror with which the reflection takes place on the outer surface so that the center of the mirror surface bulges out Concave A mirror where the reflecting surface is on the inner surface so that the center shrinks away (like a cave) Focus Where reflected parallel rays cross each other Principal axis The straight line perpendicular to the curved surface at it's center Focal point Where incident parallel rays come to a focus after reflectionAlso the image point for an object infinitely far away along the principal axis Focal length Distance between the focal point and the center of the mirror Paraxial rays Rays that make a small angle with the principal axis, so that they reflect at F Spherical abberation When rays from an image pass through the outer regions of the lens or mirror and are brought to a focus at a different point from those that pass through the center of the lens. Do Object distance, distance of the object from the center of the mirror (x value) Di Image distance, distance of the image from the center of the mirror (x value) Ho Object height, height of the object from the center of the mirror (y value) Hi Image height, height of the image from the center of the mirror (y value) Mirror equation 1/do + 1/di = 1/fWhere f is the focus, or r/2. Magnification "m", the height of the image divided by the hight of the object (hi/ho). This is also (-di/do). Index of refraction The ratio of the speed of light in a vacuum to the speed v in a given material. Denoted as n. Refraction When a ray of light changes direction as it enters a new medium Angle of refraction The angle the refracted ray makes with the normal to the surface Snell's law The angle of refraction depends on the speed of light in the two media and on the incident angle, also written as nsint = nsint. Law of refraction Snell's law, or nsint = nsint Critical angle The incident angle at which the refracted ray would skim the surface, meaning the angle of refraction would be 90 degrees. Total internal reflection When there is no refracted ray, all of the light is reflectedOnly occurs when the second medium has a lower index of refraction Fiber optics Total internal reflection used with tiny fibers as thin as a few micrometers in diameter Converging lens A lens that is thicker in the center than at the edges, which will make parallel rays converge to a point Diverging lens A lens that is thinner in the center than at the edges, and make parallel light diverge Thin lens equation Same as the mirror equation, 1/do = 1/di = 1/f Sign conventions Focal length: pos for converging, neg for divergingDi: pos if image is on opposite side of the lens, neg if same sideHi: pos if upright, neg if inverted Authormegame623 ID152338 Card SetCh 23 vocab DescriptionCh 23, geometric optics Updated2012-05-05T18:52:26Z Show Answers