Mirrors And Lenses

1. Mirrors And Lenses Chapter 23

2. Introduction • Images can be formed by plane or spherical mirrors and by lenses. • Ray diagrams will be used

3. Plane and Curved Mirrors • Important terms: • Object distance (p) • Image • Formed where light rays actually intersect or where they appear to originate • Image distance (q)

4. Two Types of Images • Real image • Light rays actually intersect and pass through the image point. • May be formed on a screen

5. Virtual Image • Light rays only appear to come from the image point. • Cannot be formed on a screen • Example: images in flat mirrors

6. Flat Mirrors • The image distance(q)always equals the object distance(p). 23.1, 29.1

7. The image height(h’)always equals the object height(h). 23.2

8. Images are left-right reversed.

9. Images are always virtual. 186

10. Images are always upright.

11. Magnification(M) is always 1.

12. Flat Mirrors Summary • The image distance always equals the object distance. • The image height (h’) always equals the object height (h). • Images are left-right reversed. • Images are always virtual. • Images are always upright. • Lateral magnification (M) is always 1.

13. Applications of Flat Mirrors • Rearview mirrors in cars • Dressing room mirrors • Bathroom mirrors 242, 29.2

14. Concave Mirrors • Concave mirrors are a part of a sphere. 236, 380

15. Light reflects from the inner surface.

16. Images formed may be real or virtual. • The type of image depends upon the object location.

17. Images may be upright or inverted.

18. Concave mirrors are sometimes called converging mirrors.

19. The focal length is positive.

20. Concave Mirrors Summary • Are a part of a sphere • Light reflects from the inner surface. • Images formed may be real or virtual. • Depends upon object location • Images may be upright or inverted. • Sometimes called converging mirrors • Focal length is positive.

21. Important Terms • Principal axis • Image point • Image distance (q) • Object distance (p) • Center of curvature C • Radius of curvature R • Focal point (F) • Focal length (f) 23.9

22. Spherical Aberration • Spherical aberration is an undesirable characteristic that is present in all spherical mirrors • It may be eliminated by using parabolic mirrors.

23. Parabolic Mirror Applications • Satellite dishes • Car headlights • Flashlights • Projector bulbs • Astronomical telescopes

24. Ray Diagrams • Front side and back side of the mirror • Light rays are always in front of the mirror. • This is taken to be the left side.

25. Three Important Rays • The intersection of any two rays will locate the image. • Parallel rays that come from infinity always pass through the focal point • When the object is at infinity, the image is at the focal point 382, 188, 382, 383

26. The paths of light rays are reversible. 238

27. Equations for Concave Mirrors • Magnification equation: • The mirror equation

28. Applications of Concave Mirrors • Shaving mirrors • Makeup mirrors • Solar cookers

29. Convex Mirrors • Convex mirrors are a part of a sphere. 380

30. Light reflects from the outer surface.

31. Images formed are always virtual. • They always lie behind the mirror.

32. Images are always upright.

33. Convex mirrors are sometimes called diverging mirrors.

34. The focal length is negative.

35. Convex Mirrors Summary • Are a part of a sphere • Light reflects from the outer surface • Images formed are always virtual • They always lie behind the mirror. • Images are always upright • Sometimes called diverging mirrors • Focal length is negative

36. Ray Diagrams for Convex Mirrors • Front side and back side of the mirror • Light rays are always in front of the mirror.

37. Ray Diagrams • See Figure 23.11 • Three important rays (see pg. 765) 23.11, 240, 384, 23.12

38. Rays that come from infinity always pass through the focal point. • When the object is at infinity, the image is at the focal point.

39. The intersection of two rays will locate the image.

40. Equations for Convex Mirrors • These equations are the same as before. • Magnification equation • The mirror equation

41. Sign Conventions for Mirrors • SeeTable 23.1on page 765

42. Applications of Convex Mirrors • Side view mirrors on cars • Shoplifting mirrors

43. Questions 1 - 4, 7 Pg. 783

44. Images Formed By Refraction • Sign conventions • See Table 23.2 on page 770

45. Apparent Depth • Flat refracting surfaces • Apparent Depth(q)vs. Actual Depth(p) • n1 is below the surface 23.16, 243

46. Atmospheric Refraction • The Sun is not where it appears to be. • It can be seen even though it is below the horizon. • Sun dogs and Moon dogs • Halos on cold winter days or nights • Refraction through hexagonal ice crystals • Mirages 23.21

47. Thin Lenses • A thin lens is a piece of glass or plastic which is ground so that its surfaces are segments of either spheres or planes. • A thin lens acts like two prisms.

48. Refraction in Optical Instruments • Thin lenses are used to form images by refraction in optical instruments • Cameras • Projectors • Microscopes • Telescopes • Binoculars • Magnifying glasses 248, 249

49. The Thin Lens Equation • The lens equation is virtually identical to the mirror equation. 23.23

50. Common Lens Shapes • Converging lenses • Biconvex • Convex-concave • Plano-convex • Diverging lenses • Biconcave • Convex-concave • Plano-concave 64, 66, 67