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Curved mirrors

Curved mirrors. General info Drawing ray diagrams. LOCATION OF CURVED MIRRORS IN THE WORLD. Other objects that act like a curved mirror. Example where the concentration of light to one location (focal point) is used to heat water. Solar oven. Focal point.

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Curved mirrors

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  1. Curved mirrors General info Drawing ray diagrams

  2. LOCATION OF CURVED MIRRORS IN THE WORLD

  3. Other objects that act like a curved mirror

  4. Example where the concentration of light to one location (focal point) is used to heat water

  5. Solar oven

  6. Focal point Place where all parallel light rays meet after they reflect off a concave mirror Distance from mirror to closest point on mirror is focal length

  7. The reverse is also true If light passes through or originates from the focal point, then the reflected rays will be parallel to the PA

  8. Examples of use

  9. OTHER PARTS OF THE ELECTROMAGNETIC SPECTRUM ACT THE SAME WAY AS LIGHT

  10. Dishes

  11. TYPES OF CURVED MIRRORS

  12. Convex and Concave Convex Concave

  13. CONCAVE MIRRORS

  14. 5 concave Locations for the object Beyond CP At CP Between CP and FP At FP Between FP and V

  15. When object is between V and F Rays will diverge To find virtual image, extend the reflected rays across the mirror to the opposite side These extensions are called the apparent light rays and are used by the mind to form virtual image

  16. CONVEX MIRRORS

  17. Draw 2 more diagrams 1 where the object is far away from the mirror 1 where the object is close to the mirror

  18. Convex mirror ray diagrams Different side of the curve is mirrored

  19. RAY DIAGRAMS FOR CURVED MIRRORS Graphical interpretation of the reflection of light off curved mirrors

  20. BASIC FEATURES ON ALL DIAGRAMS

  21. Determine location of images Two methods Graphical Mathematical

  22. Graphical Method to determine image characteristics This method will be able to determine images: Location Relative size (compared to object) Orientation (relative to Principal axis) if image is Virtual or Real

  23. General preparations Find something that can be used to make the curve of the mirror Fold paper hot-dog style Draw line down fold, label principal axis

  24. Principal axis Line that splits mirror in half Goes through vertex point Label vertex point V

  25. Drawing the mirror We will work with a cross-section image of the mirror Show the paths of light rays that reflect off mirror Curved section of protractor becomes cross section of mirror

  26. Draw a concave mirror on your paper Place protractor on right end of paper Center protractor on Principal axis (PA) Make sure mirror is concave towards rest of the paper

  27. Location of vertex Intersection of principal axis and mirror

  28. Center Point of curvature DO NOT remove protractor from paper Mark the center point of the protractor on the PA. Label “C” This is the center point

  29. Focal point Point in front of the mirror, where all rays parallel to principal axis will reflect through

  30. Location of focal point Focal point is located halfway between the center point and the vertex

  31. Draw an object Need to draw a cross section of an object Bottom rests on PA Try a banana, rectangle or arrow Draw about ¾ of an inch high Location of object relative to mirror will be different for each diagram

  32. For each drawing: Title in upper left corner of drawing PA, C, F, V all drawn or labeled 3. 2 light rays must be drawn 4. Image drawn in correct place, orientation

  33. Hints for good drawings: Use a thin object ¾ to 1 inch tall Need one more type of ray path that does not involve the focal point Most mirrors drawn to the far right of paper Except for the object place between F and V Put mirror in middle of paper

  34. PATHS TAKEN BY LIGHT ON DIAGRAMS

  35. General idea Light can bounce off an object and travel in all possible directions To find the position of the image, find the location where at least 2 light rays intersect that reach your eyes

  36. The 4 easiest rays to draw Of all the countless possible rays to use, 4 paths are used because they pass through specific points, move parallel to the principal axis and/or where angle of incidence = angle of reflectance

  37. Common light paths traveled

  38. How rays reflect off concave mirror

  39. Remember Virtual images are formed in your mind, where apparent light rays meet. Real images are formed when real light rays that bounce off the mirror intersect in space.

  40. How to draw the rays for convex mirror

  41. Converging rays, diverging rays Converging rays come together at a point Diverging rays do not intersect

  42. RESULTS WHEN SOURCE OF LIGHT IS INFINITELY FAR AWAY

  43. Where is image formed from sunlight, moonlight or the light of stars? The distance from those objects to earth can be considered infinitely far away. The only rays of the sun that intersect one point of the earth are all parallel to each other The image will form on a plane perpendicular to the principal axis that includes the focal point

  44. Spherical Aberration Inaccuracies introduced into the diagrams because the curve used was part of a circle instead of a parabola All intersections of light paths will not form on the image plane We use a circle because it is easier to create with the material at hand

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