# Chapter 23; Mirrors and Lenses

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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:
POSITIVE!
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
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
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
 Author: Anonymous ID: 15434 Card Set: Chapter 23; Mirrors and Lenses Updated: 2010-04-21 02:12:43 Tags: Mirrors Lenses Physics Folders: Description: Chapter 23 Test Study; Physics Show Answers: