1. Light
Chapter 13

2. Ch13 Sec 1 The Behavior of Light

3. Light and Matter Objects must reflect light to be seen.
Opaque materials do not allow light to pass through them; they only absorb and reflect light

4. Light and Matter Objects must reflect light to be seen.
Opaque materials do not allow light to pass through them; they only absorb and reflect light
Some light passes through translucent materials.

5. Light and Matter Objects must reflect light to be seen.
Opaque materials do not allow light to pass through them; they only absorb and reflect light
Some light passes through translucent materials.
Transparent materials allow almost all light to pass through them; only a little light is absorbed and reflected.

6. Reflection of light
Reflection of light – a light wave strikes an object and bounces off.
Law of Reflection – angle at which light strikes a surface is the same as the angle at which it is reflected

7. Regular Reflection
Regular reflection – reflection of light waves from a smooth surface

8. Diffuse Reflection
Diffuse reflection – reflection of light waves from a rough surface

10. Refraction of Light
Refraction of light - change in the speed of a light wave when it passes from one material to another

11. Index of refraction
The index of refraction indicates how much a material reduces the speed of light; the more light is slowed, the greater the index of refraction.

12. Prisms
Separate white light into visible spectrum based on light wavelength

13. Rainbows
Caused by water droplets refracting wavelengths of sunlight

14. Chapter 13 Section 2 Light and Color

15. Colors…
Colors are determined by wavelength of light an object reflects.
White objects reflect all colors of visible light.
Black objects absorb all colors of visible light.

16. Colors…
Colors are determined by wavelength of light an object reflects.
White objects reflect all colors of visible light.
Black objects absorb all colors of visible light.
Filter – is a transparent material that absorbs all colors except the color or colors it transmits
Filters can make objects appear to be different colors.

17. Seeing Color Light enters the eye and is focused on the retina.
Retina – made up of two types of cells that absorb light

18. Seeing Color… Light enters the eye and is focused on the retina.
Retina – made up of two types of cells that absorb light
Cones – distinguish colors and detailed shapes; most effective in daytime vision
Rods – sensitive to dim light; most effective in nighttime vision

19. Test Name: Ishihara Test
Colorblindness Tests
Normal color:
yellow square &
faint brown circle
Colorblind sees:
yellow square
Colorblind sees:
the number 17
Normal Color sees:
the number 15
Test Name: Ishihara Test

20. Colorblindness
Results from when one or more sets of cones do not function properly

21. Mixing colors
Pigment – colored material that absorbs some colors and reflects others

22. Mixing colors
Pigment – colored material that absorbs some colors and reflects others
Primary colors of light – Red, Green, and Blue
Primary colors of pigment – magenta, cyan, and yellow

23. Mixing colors
Pigment – colored material that absorbs some colors and reflects others
Primary colors of light – Red, Green, and Blue
Primary colors of pigment – magenta, cyan, and yellow
Primary colors of light are additive colors – combine to form white
Primary colors of pigments are subtractive colors – combine to form black, the absence of reflected light

24. Producing Light
Chapter 13 Section 3

25. Incandescent lights
Hot tungsten wire glows; gives off light and heat

26. Fluorescent lights
Electrons collide with gas atoms, releasing ultraviolet radiation absorbed by phosphorus lining the bulb; gives off light
Why are these better than Incandescent bulbs?
Less energy used
longer lasting

27. Neon lights
Tubes filled with gas (usually neon) produce light from electron collisions; different colors can be made by adding different gases

28. Sodium-vapor lights
Heated neon gas glows and warmth turns sodium into a vapor, producing a yellow-orange glow; used for outdoor lighting.

29. Tungsten-halogen lights
Have a filament and gas enclosed in a glass bulb to produce intensely bright light

30. Lasers
Light beam produced when identical atoms send off identical light waves; can be made from gases, liquids, or solids
FYI – LASER – Light Amplification by Stimulating Emissions of Radiation

31. Lasers
Light beam produced when identical atoms send off identical light waves; can be made from gases, liquids, or solids
Lasers produce coherent light – waves of some wavelength are aligned, and travel same direction
Incoherent light – waves of multiple wavelengths are not aligned, travel in many directions

32. Using Light
Chapter 13 Section 4

33. Holography
Process used to create a three-dimensional photographic image of an object
Illuminating objects with laser light produces holograms.
Holographic images are difficult to copy.

34. Optical Fibers
Use a process called Total Internal Reflection in order to transfer information coded in light beams.
Total internal reflection – light strikes a surface between two materials and is completely reflected back to the first material.

35. Total internal reflection