Interactions of Light with Matter Chapter 3 Section 2
description
Transcript of Interactions of Light with Matter Chapter 3 Section 2
![Page 1: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/1.jpg)
Interactions of Light with MatterInteractions of Light with MatterChapter 3 Section 2Chapter 3 Section 2
![Page 2: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/2.jpg)
How does light travel?How does light travel?
• In a straight line unless it hits object or is absorbed
![Page 3: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/3.jpg)
What is reflection?What is reflection?
• Light bouncing off an object
• Changes direction of light
• Like a ball bouncing off ground
![Page 4: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/4.jpg)
What is “Law of Reflection”?What is “Law of Reflection”?
• Angle made by light hitting surface = angle of light reflected
![Page 5: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/5.jpg)
What are the types of What are the types of Reflection”?Reflection”?
• Regular reflection: light reflects off mirror at same angle; surface smooth/ shiny – mirror
![Page 6: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/6.jpg)
What are the types of What are the types of Reflection?Reflection?
• Diffuse reflection: light reflects in many directions; surface rough/bumpy – wall; can’t see reflection
![Page 7: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/7.jpg)
What are the types of What are the types of Reflection?Reflection?
• Regular (Spectacular)
• Diffuse
![Page 8: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/8.jpg)
What are the light sources?What are the light sources?
• Luminous - object produces visible light
• Illuminated – object needs a separate light source to be seen
• Importance? Sight needs light; to be seen must either be luminous or be illuminated
![Page 9: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/9.jpg)
Interactions of Light with MatterInteractions of Light with MatterChapter 3 Section 2 Part IIChapter 3 Section 2 Part II
![Page 10: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/10.jpg)
What is absorption of light?What is absorption of light?
• Transfer of energy to particles of matter
• Explains why light dims as it moves from light source: more particles absorb the energy, making it dimmer
![Page 11: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/11.jpg)
What is scattering of light?What is scattering of light?• Light moving in all
directions after colliding with particles
• Fog is good example• Allows you to see
outside beam, but it dims
• Explains why sky is blue: shorter wavelength is scattered more than other colors, so you see more of it
![Page 12: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/12.jpg)
How does light interact with matter? How does light interact with matter?
• Reflected – bounces off• Transmitted – passes
through matter; example through a window
• Absorbed – transfer light energy to matter; makes object feel warmer
• (next section) Refracted – wave is bent
![Page 13: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/13.jpg)
How does transparent, translucent, How does transparent, translucent, or opaque matter matter? or opaque matter matter?
• Transparent: easily transmits visible light (air, glass, H2O)
• Translucent: transmits light but also scatters it (wax paper)
• Opaque: doesn’t transmit light (metal, wood, textbook)
![Page 14: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/14.jpg)
How is an object’s color How is an object’s color determined? determined?
• Wavelength determines• Eyes receive light• Eyes send messages to
brain• Brain interprets signals
as colors• Long = red / short = violet
/ mixture of waves = combination of colors
![Page 15: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/15.jpg)
With opaque objects, how does With opaque objects, how does reflection and absorption impact reflection and absorption impact
the color?the color?• Light hits opaque
object:Some waves reflected, see that colorSome absorbed, don’t see that color
![Page 16: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/16.jpg)
How do we see a strawberry as How do we see a strawberry as red?red?
• Red wavelengths reflected; other colors’ wavelengths absorbed
![Page 17: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/17.jpg)
What makes something white?What makes something white?
• All colors’ wavelengths are reflected
![Page 18: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/18.jpg)
What makes something What makes something blackblack??
• All colors’ wavelengths are absorbed
![Page 19: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/19.jpg)
What about color in non-opaque What about color in non-opaque objects?objects?
• Transparent: Colorless in white light because all light waves pass through (transmit). Think of glass window.
• Translucent: Shows color of wavelength reflected or transmitted; all others absorbed. Think of stained glass.
![Page 20: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/20.jpg)
How do pigments produce How do pigments produce color?color?
• Pigment = material that absorbs some colors of light and reflects other
![Page 21: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/21.jpg)
What has pigment?What has pigment?
• Pigment is in almost everything
![Page 22: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/22.jpg)
What are two examples of What are two examples of pigments?pigments?
• Melanin = pigment for skin color
• Chlorophyll = plant color
![Page 23: Interactions of Light with Matter Chapter 3 Section 2](https://reader033.fdocuments.in/reader033/viewer/2022042822/56816003550346895dcf02cb/html5/thumbnails/23.jpg)
What happens when pigments are What happens when pigments are mixed?mixed?
• Each pigment absorbs at least 1 color
• Mix pigments, more colors are taken away; color subtraction