1. 1 23 Mirrors & Lenses Mirrors Lenses Lens Maker Equation 43, 67, 85, 89, 92, 93.

2. 2 Images Real: light converges to a point. Ex. magnifying glass used to start fire. Virtual: light diverges (or appears to have diverged) from a point. Ex. Any “.” on this screen can be seen anywhere in room.

3. 3 Ray Diagrams axis, focal point/plane, mirror plane/V r, focal distance f = r/2 do, di, f

4. 4 concave mirror images

5. Animated Mirror Diagrams http://www.glenbrook.k12.il.us/gbssci/phys /Class/refln/u13l3d.htmlhttp://www.glenbrook.k12.il.us/gbssci/phys /Class/refln/u13l3d.html

6. 6 convex mirror images always “virtual”, “upright”, “diminished”

7. 7 Mirror Equations relate do, di & f. lateral magnification (LM) = hi/ho. you must learn the sign conventions to use these formulas

8. 8 Plane Mirror: Virtual Image di = -do f = infinity

9. 9 Ex. Object sits 25cm in front of concave mirror with f = 15cm. Calculate the image distance and magnification. Check with a ray diagram.

10. 10 thin lenses symmetric focal points converging (f>0), diverging (f<0)

11. 11 converging lens rays

12. 12 converging lens images

13. 13 diverging lens images

14. 14 lens power power = 1/(focal-length(meters)) unit: [D, diopters, 1/m] used for corrective lenses Ex. near-sighted person P = -5.0D f = 1/P = 1/(-5) = -0.2m = -20cm.

15. 15 Summary mirror & lens parameters ray diagramming, image formation and characterization calculation of parameters

16. 16 Paraxial Approximation Focus isn’t exact for a spherical mirror (but rays near axis focus well) Focus is sharp for parabolic mirror (aspheric)

17. 17 ??do?? #43 Silvered sphere R = 20cm, f = -10cm hi = 1/3 ho LM = hi/ho = -di/do = 1/3. -3di = do 1/do + 1/di = 1/f 1/(-3di) + 1/di = 1/(-10)

18. 18 ??do?? #67 f = +10cm lens, what do causes LM = -2. LM = hi/ho = -di/do = -2 di = 2do 1/do + 1/di = 1/f 1/do + 1/2do = 1/10

19. 19 imbedded object image distance < object distance s’ = s/n

20. 20 Lens Maker’s Equation Ex. radii = 20cm, n = 1.5, in air & water: