The back side Where virtual images are formed Diagram for Signs Sign

# The back side where virtual images are formed diagram

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The back side Where virtual images are formed Diagram for Signs Sign Conventions for Mirrors Ray Diagrams A ray diagram can be used to determine the position and size of an image. They are graphical constructions which tell the overall nature of the image. They can also be used to check the parameters calculated from the mirror and magnification equations. Drawing A Ray Diagram To make the ray diagram, you need to know The position of the object The position of the center of curvature Three rays are drawn They all start from the same position on the object The intersection of any two of the rays at a point locates the image. The third ray serves as a check of the construction. The Rays in a Ray Diagram Ray 1 is drawn parallel to the principle axis and is reflected back through the focal point, F. Ray 2 is drawn through the focal point and is reflected parallel to the principle axis. Ray 3 is drawn through the center of curvature and is reflected back on itself. Notes About the Rays The rays actually go in all directions from the object. The three rays were chosen for their ease of construction. The image point obtained by the ray diagram must agree with the value of q calculated from the mirror equation. Ray Diagram Examples Note the changes in the image as the object moves through the focal point. Ray Diagram for Concave Mirror, p > R The object is outside the center of curvature of the mirror. The image is real. The image is inverted. The image is smaller than the object. Ray Diagram for a Concave Mirror, p < f The object is between the mirror and the focal point. The image is virtual. The image is upright. The image is larger than the object. Ray Diagram for a Convex Mirror The object is in front of a convex mirror. The image is virtual. The image is upright. The image is smaller than the object. Notes on Images With a concave mirror, the image may be either real or virtual. When the object is outside the focal point, the image is real. When the object is at the focal point, the image is infinitely far away. When the object is between the mirror and the focal point, the image is virtual. With a convex mirror, the image is always virtual and upright. As the object distance increases, the virtual image gets smaller. Images Formed by Refraction Rays originate from the object point, O, and pass through the image point, I When n 2 > n 1 , Real images are formed on the side opposite from the object. Sign Conventions for Refracting Surfaces Flat Refracting Surface The image formed by a flat refracting surface is on the same side of the surface as the object. The image is virtual.  #### You've reached the end of your free preview.

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• Spring '08
• Loch
• Light, Geometrical optics, rays
• • • 