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Ray Diagrams

Ray Diagrams. Outline. Reflection Mirrors Plane mirrors Spherical mirrors Concave mirrors Convex mirrors Refraction Lenses Concave lenses Convex lenses. A ray of light is an extremely narrow beam of light. All visible objects emit or reflect light rays in all directions.

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Ray Diagrams

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  1. Ray Diagrams

  2. Outline • Reflection • Mirrors • Plane mirrors • Spherical mirrors • Concave mirrors • Convex mirrors • Refraction • Lenses • Concave lenses • Convex lenses

  3. A ray of light is an extremely narrow beam of light.

  4. All visible objects emit or reflect light rays in all directions.

  5. Our eyes detect light rays.

  6. We see images when light rays converge in our eyes. converge: come together

  7. Mirrors It is possible to see images in mirrors. image object

  8. normal reflected ray incident ray θr θi Mirror Reflection(bouncing light) Reflection is when light changes direction by bouncing off a surface. When light is reflected off a mirror, it hits the mirror at the same angle (the incidence angle, θi) as it reflects off the mirror (the reflection angle, θr). The normal is an imaginary line which lies at right angles to the mirror where the ray hits it.

  9. Mirrors reflect light rays.

  10. Plane Mirrors(flat mirrors) How do we see images in mirrors?

  11. Plane Mirrors(flat mirrors) object image How do we see images in mirrors? Light reflected off the mirror converges to form an image in the eye.

  12. Plane Mirrors(flat mirrors) object image How do we see images in mirrors? Light reflected off the mirror converges to form an image in the eye. The eye perceives light rays as if they came through the mirror. Imaginary light rays extended behind mirrors are called sight lines.

  13. Plane Mirrors(flat mirrors) object image How do we see images in mirrors? Light reflected off the mirror converges to form an image in the eye. The eye perceives light rays as if they came through the mirror. Imaginary light rays extended behind mirrors are called sight lines. The image is virtual since it is formed by imaginary sight lines, not real light rays.

  14. Spherical Mirrors(concave & convex)

  15. r Concave & Convex(just a part of a sphere) • C • F f C: the center point of the sphere r: radius of curvature (just the radius of the sphere) F: the focal point of the mirror (halfway between C and the mirror) f: the focal distance, f = r/2

  16. optical axis Concave Mirrors(caved in) • F Light rays that come in parallel to the optical axis reflect through the focal point.

  17. optical axis Concave Mirror(example) • F

  18. optical axis Concave Mirror(example) • F The first ray comes in parallel to the optical axis and reflects through the focal point.

  19. optical axis Concave Mirror(example) • F The first ray comes in parallel to the optical axis and reflects through the focal point. The second ray comes through the focal point and reflects parallel to the optical axis.

  20. optical axis Concave Mirror(example) • F The first ray comes in parallel to the optical axis and reflects through the focal point. The second ray comes through the focal point and reflects parallel to the optical axis. A real image forms where the light rays converge.

  21. optical axis Concave Mirror(example 2) • F

  22. optical axis Concave Mirror(example 2) • F The first ray comes in parallel to the optical axis and reflects through the focal point.

  23. optical axis Concave Mirror(example 2) • F The first ray comes in parallel to the optical axis and reflects through the focal point. The second ray comes through the focal point and reflects parallel to the optical axis.

  24. optical axis Concave Mirror(example 2) • F The first ray comes in parallel to the optical axis and reflects through the focal point. The second ray comes through the focal point and reflects parallel to the optical axis. The image forms where the rays converge. But they don’t seem to converge.

  25. optical axis Concave Mirror(example 2) • F The first ray comes in parallel to the optical axis and reflects through the focal point. The second ray comes through the focal point and reflects parallel to the optical axis. A virtual image forms where the sight rays converge.

  26. optical axis Your Turn(Concave Mirror) object • F concave mirror • Note: mirrors are thin enough that you just draw a line to represent the mirror • Locate the image of the arrow

  27. optical axis Your Turn(Concave Mirror) object • F concave mirror • Note: mirrors are thin enough that you just draw a line to represent the mirror • Locate the image of the arrow

  28. optical axis Convex Mirrors(curved out) • F Light rays that come in parallel to the optical axis reflect from the focal point. The focal point is considered virtual since sight lines, not light rays, go through it.

  29. optical axis Convex Mirror(example) • F

  30. optical axis Convex Mirror(example) • F The first ray comes in parallel to the optical axis and reflects through the focal point.

  31. optical axis Convex Mirror(example) • F The first ray comes in parallel to the optical axis and reflects through the focal point. The second ray comes through the focal point and reflects parallel to the optical axis.

  32. optical axis Convex Mirror(example) • F The first ray comes in parallel to the optical axis and reflects through the focal point. The second ray comes through the focal point and reflects parallel to the optical axis. The light rays don’t converge, but the sight lines do.

  33. optical axis Convex Mirror(example) • F The first ray comes in parallel to the optical axis and reflects through the focal point. The second ray comes through the focal point and reflects parallel to the optical axis. The light rays don’t converge, but the sight lines do. A virtual image forms where the sight lines converge.

  34. object optical axis Your Turn(Convex Mirror) • F convex mirror • Note: mirrors are thin enough that you just draw a line to represent the mirror • Locate the image of the arrow

  35. object optical axis Your Turn(Convex Mirror) image • F convex mirror • Note: mirrors are thin enough that you just draw a line to represent the mirror • Locate the image of the arrow

  36. Lensmaker’s Equation • ƒ = focal length • do = object distance • di = image distance • if distance is negative the image is behind the mirror

  37. Magnification Equation • m = magnification • hi = image height • ho = object height • If height is negative the image is upside down • if the magnification is negative • the image is inverted (upside down)

  38. normal θi air glass block θr θi air θr normal Refraction(bending light) Refraction is when lightbends as it passes from one medium into another. When light traveling through air passes into the glass block it is refracted towards the normal. When light passes back out of the glass into the air, it is refracted away from the normal. Since light refracts when it changes mediumsit can be aimed. Lenses are shaped so light is aimed at a focal point.

  39. Lenses The first telescope, designed and built by Galileo, used lenses to focus light from faraway objects, into Galileo’s eye. His telescope consisted of a concave lens and a convex lens. light from object convex lens concave lens Light rays are always refracted (bent) towards the thickest part of the lens.

  40. • F optical axis Concave Lenses Concave lenses are thin in the middle and make light rays diverge (spread out). If the rays of light are traced back (dotted sight lines), they all intersect at the focal point (F) behind the lens.

  41. optical axis Concave Lenses • F Light rays that come in parallel to the optical axis diverge from the focal point. The light rays behave the same way if we ignore the thickness of the lens.

  42. optical axis Concave Lenses • F Light rays that come in parallel to the optical axis still diverge from the focal point.

  43. optical axis Concave Lens(example) • F The first ray comes in parallel to the optical axis and refracts from the focal point.

  44. optical axis Concave Lens(example) • F The first ray comes in parallel to the optical axis and refracts from the focal point. The second ray goes straight through the center of thelens.

  45. optical axis Concave Lens(example) • F The first ray comes in parallel to the optical axis and refracts from the focal point. The second ray goes straight through the center of the lens. The light rays don’t converge, but the sight lines do.

  46. optical axis Concave Lens(example) • F The first ray comes in parallel to the optical axis and refracts from the focal point. The second ray goes straight through the center of the lens. The light rays don’t converge, but the sight lines do. A virtual image forms where the sight lines converge.

  47. object optical axis Your Turn(Concave Lens) • F concave lens • Note: lenses are thin enough that you just draw a line to represent the lens. • Locate the image of the arrow.

  48. object optical axis Your Turn(Concave Lens) • F image concave lens • Note: lenses are thin enough that you just draw a line to represent the lens. • Locate the image of the arrow.

  49. Convex Lenses Convex lenses are thicker in the middle and focus light rays to a focal point in front of the lens. The focal length of the lens is the distance between the center of the lens and the point where the light rays are focused.

  50. optical axis Convex Lenses • F

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