Chapter 23; Mirrors and Lenses

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Chapter 23; Mirrors and Lenses
2010-04-20 22:12:43
Mirrors Lenses Physics

Chapter 23 Test Study; Physics
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  1. A Reflection is:
    When a wave reaches a boundary between two mediums and is turned around
  2. Total Reflection
    reflection boundary with a more rigid medium
  3. Partial Reflection
    reflection boundary with a less rigid medium
  4. Plane Mirrors are:
    Flat mirrors which form a virtual image
  5. Plane Mirror Rules
    • - Images same size and orientation
    • - Image left to right
    • - Must be half the height of the object to see entire object
  6. Principle Axis
    Line perpendicular to the mirror; passes through the center of curvature
  7. Center of Curvature
    The geometric center fo the sphere
  8. Focal Length
    1/2 of the Center of Curvature
  9. Image Distance
    Distance from the mirror to the object
  10. Concave Mirror - Outside Focal Length
    • - real image (formed in front of the mirror)
    • - image inverted (always)
    • - image smaller than object
    • - focal length positive
  11. Concave Mirror - Inside Focal Length
    • - virtual image (image formed behind mirror)
    • - image upright
    • - image larger than object
    • - focal length positive
  12. 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
  13. Any light ray which approaches the mirror parallel to the principle axis will:
    be reflected through the focal point
  14. Any light ray which passes through the focal point will be:
    reflected parallel to the principle axis
  15. Image distances are negative if:
    the image is virtual
  16. Image distances are positive if:
    the image is real
  17. Object distances are always:
  18. Mirror and Lens Equations
    • 1/f = 1/di + 1/do
    • m = hi/ho = -di/do
  19. If magnification is positive:
    the image is upright
  20. If magnification is negative:
    the image is inverted
  21. Power Equation for Lenses
    P = 1/f

    measured in diopters(1/m); focal lenght MUST be in meters
  22. Refraction Equation
    • nosinOi = nsinOr (no - moving out of; n - moving in to)
    • n=(sin i)/(sin r)
  23. Snell's Law & the Index of Refraction - how much a light bends at a boundary

    • 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
  24. 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
  25. Converging Lens
    Convex (curve out); make light converge earlier; focal length positive
  26. Diverging Lens
    Concave (curve in); diverge light; focal length negative
  27. 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
  28. 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
  29. The Eye
    • - lens focuses image on the retina
    • - image formed in front of retina = nearsighted
    • - image formed behind the retina = farsighted
  30. 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