Chapter 18: Light

1. Chapter 18: Light Final Chapter of Material on the Final!

2. Essential Questions What are some sources of light, and how does light travel? What can happen to light that strikes matter? Why do objects appear to have different colors? How does light reflect from smooth surfaces and rough surfaces? What types of mirrors can produce real or virtual images? What happens to light as it moves from one transparent substance to another? How do convex lenses and concave lenses affect light? How do eyes detect light and color?

3. Yay or Nay? Both the sun and the Moon produce their own light The color of an object depends on the light that strikes it Mirrors are the only surfaces that reflect light The image in a mirror is always right-side up A prism adds color to light When light moves from air into water or glass, it travels more slowly A laser will burn a hold through your skin Telephone conversations can travel long distances as light waves

4. Section 1: Light, Matter, and Color produce not • Light is electromagnetic radiation that you can see • EM radiation has both wave and particle properties • Particles are called photons • Luminousobjects ____________ visible light • Light source • Illuminated objects are visible objects that are _____ a light source • Due to the light around it (reflection)

5. Section 1: Light, Matter, and Color Reflected Absorbed Transmitted • Light travels as waves moving away from a source • When light strikes objects, it can be

6. Section 1: Light, Matter, and Color Reflection is when light bounces off an object Absorption is when light energy is transferred to the medium through which it travels Transmission is the passing of light through an object

7. Section 1: Light, Matter, and Color plastic wrap wax paper Aluminum foil • Transparent material allows almost all the light that strikes it to pass through and form a clear image • Ex: glass, ________________ • Translucentmaterial allows most of the like that strikes to it pass through and form a blurry image because some is scattered • Ex: frosted glass, ______________ • In an opaque material, light does not pass through • Ex: __________________, a book, wood

8. Section 1: Light, Matter, and Color the transfer of energy dims change direction • Absorption is ________________________ carried by light waves to particles of matter • Air absorbs some energy • Why a flashlight ______ • Farther the light source, the more light that gets absorbed • Scattering is an interaction of light with matter that causes light to ____________________ • All directions • See objects outside beam • WHY THE SKY IS BLUE!

9. Section 1: Light, Matter, and Color hits your eyes Color is about the reflection of light off materials that __________________

10. Section 1: Light, Matter, and Color • Opaque objects • The colors you see are the colors that are _______________ • __________ = ALL colors reflected • __________ = ALL colors absorbed • Translucent objects • The colors you see are the colors that are ___________________ reflected White Black transmitted

11. Section 1: Light, Matter, and Color • Only need 3 colors to make white light • Called ______________ colors of light • Combining colors of light is called color ______________ • Mixing two primary light colors makes ______________light colors Red Green Blue primary addition secondary

12. Section 1: Light, Matter, and Color • A pigment is a material that gives a substance its color by _______________ some color of light and reflecting others • _______________ pigments • Mixing pigments results in more colors being absorbed or taken away—color ________________ absorbing Primary Magenta Yellow Cyan subtraction

13. Section 2: Reflection and Mirrors reflection incidence • Reflectionis when light waves bounce off an object • EX: mirror • The Law of Reflection states that when a wave is reflected from a surface, the angle of ___________________ is equal to the angle of __________________ • The angle it comes out is the same angle it goes in

14. Regular Reflection is the reflection of light from a _________, shiny surface • All light comes out parallel Section 2: Reflection and Mirrors • Diffuse Reflection is the reflection of light from a __________ surface • Light comes out at different angles smooth rough

15. Section 2: Reflection and Mirrors flat reversed virtual images Plane Mirrors have a ________ surface. Light reflects off a mirror because it can not pass through the surface. The reflection of an object in a plane mirror is right side up and the same size as the object, but _______________ left to right. Plane mirrors form __________________________ . A virtual image is an image through which light does not travel

16. Section 2: Reflection and Mirrors Plane Mirror Ray Diagrams • First, we draw an image of the object on the other side of the mirror the same size and distance away

17. Section 2: Reflection and Mirrors Plane Mirror Ray Diagrams • Second, we draw light rays from the top and bottom of the image to the eye • Used dashed lines from behind the mirror since light doesn’t really come from there (virtual)

18. Section 2: Reflection and Mirrors Plane Mirror Ray Diagrams • Third, we join the light rays from the mirror to the object • Lines joining the object to the positions of the reflected rays on the mirror represent the incident rays by following the law of reflection.

19. Section 2: Reflection and Mirrors Location Orientation Size Type Describe the image using LOST L- _________________: location of the image (in front or behind the mirror). O- ___________________: which way the image is oriented compared to the original object (upright or inverted). S- _______: compared to original object is it same size, smaller or bigger? T- _______: is the image a real image or virtual image?

20. Section 2: Reflection and Mirrors • Let’s try! • L: • O: • S: • T:

21. Section 2: Reflection and Mirrors • Let’s try! • L: • O: • S: • T: ♥

22. Section 2: Reflection and Mirrors • Characteristics of a plane mirror image: L:Object distance from mirror ___ image distance from mirror O: Orientation is ALWAYS ____________ S: Object size ___= Image Size T: ALWAYS forms a ________ image Image is reversed- left to right = Upright = virtual

23. Section 2: Reflection and Mirrors curves inward virtual real meet Examples: automobile headlights, flashlights, Make-up mirrors concave mirror = convergent mirror A concave mirror is a mirror that __________________. They can produce either a __________ or _________image. The point at which all light rays _______ is called the focal point. The focal length is the distance along the optical axis from the mirror to the focal point

24. Concave Mirror Ray Diagrams Section 2: Reflection and Mirrors First ray comes in parallel to Principal/optical axis and reflects back to the focal point Second ray comes through the focal point and reflects back out parallel to the optical/principal axis If no lines come together, extend as dashed lines on back side of mirror—virtual image

25. Concave Mirror Ray Diagrams Section 2: Reflection and Mirrors

26. Section 2: Reflection and Mirrors • Let’s try! • L: • O: • S: • T:

27. Section 2: Reflection and Mirrors • Let’s try! • L: • O: • S: • T:

28. Section 2: Reflection and Mirrors • Characteristics of a Concave mirror image:

29. Section 2: Reflection and Mirrors outward spread out light wide angle Examples: Used in store aisles, hazardous traffic intersections, side mirrors on cars and buses. convex mirror = diverging mirror A convex mirror curves __________. The object is virtual and appears smaller and upright. Convex mirrors _________________________; allowing the mirror to show a ________________ of view.

30. Convex Mirror Ray Diagrams Section 2: Reflection and Mirrors First ray comes in parallel to Principal/optical axis and reflects back to the focal point on the opposite side Second ray comes through the focal point on the opposite side and reflects back out parallel to the optical/principal axis If no lines come together on the real side of the mirror, extend as dashed lines on back side of mirror—virtual image

31. Convex Mirror Ray Diagrams Section 2: Reflection and Mirrors

32. Section 2: Reflection and Mirrors • Let’s try! • L: • O: • S: • T:

33. Section 2: Reflection and Mirrors • Let’s try! • L: • O: • S: • T:

34. Section 2: Reflection and Mirrors • Characteristics of a convex mirror image: L: Image is ALWAYS ___________ mirror O: Orientation is ALWAYS ____________ S: Object size ___ Image Size T: ALWAYS forms a _________ image behind upright > virtual

35. Section 2: Reflection and Mirrors

36. Section 3: Refraction and Lenses bending Refraction is the __________ of a wave as it passes at an angle from one substance to another

37. Section 3: Refraction and Lenses different speeds • Why does refraction happen • Light travels at _____________________when it goes through different things • This changes the angle the light travels at

38. Section 3: Refraction and Lenses transparent bend • Lens – an object made of ________________ material that has one or two curved surfaces that can refract or ______ light. • The curvature and thickness of a lens affect the way it refracts light.

39. Section 3: Refraction and Lenses inward • A concave lens is curved __________ at the ___________ (thinnest) and the thickest part at the outside edges. • The light rays are ___________________ . • Forms a small, upright __________image. • Concave lenses cure nearsightedness when an eyeball is too long • Examples: a peep hole in a door, found in viewfinders of cameras, eyeglasses, telescopes. center spread out virtual concave lens = divergent lens

40. Concave Lens Diagrams Section 3: Refraction and Lenses First ray comes in parallel to Principal/optical axis and refracts through lined up with the focal point in front of the lens Second ray comes the center of the lens If no lines come together, extend as dashed lines on front side of lens—virtual image

41. Section 3: Refraction and Lenses • Let’s try! • L: • O: • S: • T:

42. Section 3: Refraction and Lenses • Let’s try! • L: • O: • S: • T:

43. Section 3: Refraction and Lenses outward center • A convex lens is curved __________ outward at the ____________center and is thinnest at the outer edge. • Convex lenses form either real or virtual images. • If the object is located between a convex lens and its focal point it forms an enlarged virtual image • If the object is located behind the focal point, it forms a smaller real image • The real images is upside down. • Example; microscopes, magnifying glasses, eye glasses. • Convex lenses can be used to correct farsightedness when an eyeball is too short convex lens = converging lens

44. Convex Lens Diagrams Section 3: Refraction and Lenses First ray comes in parallel to Principal/optical axis and refracts through the focal point Second ray comes the center of the lens If no lines come together, extend as dashed lines on front side of lens—virtual image

45. Section 3: Refraction and Lenses • Let’s try! • L: • O: • S: • T:

46. Section 3: Refraction and Lenses • Let’s try! • L: • O: • S: • T:

47. Section 3: Refraction and Lenses

48. Chapter 23