1. Chapter 13 Light and reflection
Section 1 Characteristics of Light
Chapter 13 Light and reflection

2. Early Concepts of Light
Ancient Greek philosophers thought light consisted of tiny particles which could enter the eye to create the sensation of vision.

3. Early Concepts of Light
Socrates and Plato thought vision resulted from streamers or filaments emitted by the eye making contact with an object

4. Early Concepts of Light
Empedocles, who was Greek, taught that light travels as waves
Christian Huygens, Dutch scientist, also thought light was a wave

5. Early Concepts of Light
In 1905 Einstein published the photoelectric effect: light consists of particles called photons
Scientists now agree light has a dual wave- particle nature meaning it behaves as both

6. Electromagnetic Spectrum
Consists of: 1. Radio Waves
2. Microwaves
3. Infrared (IR) Waves
4. Visible Light
5. Ultraviolet (UV) Light
6. X rays
7. Gamma Rays

7. Speed of Light
300,000 km/s in a vacuum

8. Light-Year The distance light travels in one year Example:
If a beam of light were to travel around the Earth it would make 7.5 trips around the Earth in one second.

9. Electromagnetic Waves
Wave that is partly electric and partly magnetic.
These make up the electromagnetic spectrum

11. Chapter 12 The Electromagnetic Spectrum

12. Electromagnetic Waves
DO NOT require a medium
Made by vibrating electric charges

13. Electromagnetic Wave Energy
These waves carry radiant energy

14. Electromagnetic Wave Speed
All E. Waves travel at 300,000 km/s in a vacuum
Called the speed of light

15. Only a very small part of the total energy given off by the sun reaches Earth. The sun gives off energy as EM waves in all directions. Most of this energy travels away in space.

16. Electromagnetic Spectrum
Consists of: 1. Radio Waves
2. Microwaves
3. Infrared (IR) Waves
4. Visible Light
5. Ultraviolet (UV) Light
6. X rays
7. Gamma Rays

17. Chapter 22
Section 2 The Electromagnetic Spectrum

18. Visible Light Spectrum
What are the colors of the visible light spectrum?

19. Section 1 The Behavior of Light
Chapter 13 Light

20. Light and Matter
In order for you to see an object, it must reflect light back to your eyes

21. Light and Matter Objects can: absorb light reflect light
transmit light
Depends on type of matter

22. Opaque Material This type of material only absorbs and reflects light
No light passes through it
You cannot see what is inside an opaque cup

23. Translucent Material Allows some light to pass though
You cannot see clearly through this material but you can see a shape
Example: Frosted Glass Window

24. Transparent Material Transmits almost all the light
You can see objects clearly through a transparent material
Example: Glass Window

25. Chapter 13 Light and Reflection
Section 2 & Section 3
Chapter 13 Light and Reflection

26. Reflection
The change in direction of an electromagnetic wave (ex: light) at a surface that causes it to move away from the surface
Diffuse reflection- light reflected in many different directions from a rough, textured surface
Specular reflection- light reflected in one direction from a smooth, shiny surfaces

27. Angle of incidence- angle made by the incident ray and the normal
Angle of reflection- angle made by the reflected ray and the normal
angle of incidence = angle of reflection

28. Mirrors Simplest is a flat mirror Flat mirrors form virtual images
Virtual image- image that forms at a point from which light rays appear to come but do not actually come

29. Concave Mirror
A mirror whose reflecting surface is a segment of the inside of a sphere
Used when an object needs to be magnified (i.e. a dressing-table mirror)

30. Convex Mirror
A mirror whose reflecting surface is an outward-curved segment of a sphere
Take objects from a large field of view and produce a small image
Ex: Side-view mirrors on a car

31. Parabolic Mirrors Eliminate spherical aberration
Spherical aberration- occurs when parallel rays converge away from the mirror’s focal point
Reflecting telescopes use parabolic mirrors

32. Chapter 13 light and reflection
Section 4
Chapter 13 light and reflection

33. Additive primary colors
Red, blue, and green light
These colors when added together produce white light

34. Subtractive primary colors
Colors of magenta, yellow, and cyan
When these three primary colors are combined the resulting color is black

35. Linear Polarization
Waves with vertical electric field oscillations are separated from waves with horizontal electric field oscillations
This produces a beam of light with waves oriented in the same direction

36. Linear Polarization cont’d
Ex: Polarized sunglasses
These cut down on glare