1. Bellwork (4/22) What is interference?
The result of the superposition of two or more waves

2. Waves Demos and Notes
4/22/14

3. Mechanical Waves The energy of the wave travels through the medium
The medium itself stays in the same location

4. Mechanical Waves Slinky Seismic (Earthquakes)
Water ripples (Surface waves)
Ocean Waves
Sound
String or rope

5. Mechanical vs. EM waves Mech. Waves NEED a medium to travel through
EM Waves don’t need a medium
Mech. Longitudinal waves can propagate in fluids and solids
Mech. Transverse waves can propagate only in solids

6. Bellwork (4/24) What is the physics concept behind 3-D movies?
Light Polarization

7. Today’s Agenda Finish the Activity
Go over notes from Yesterday’s Activity
Start the next lab

8. Properties of Light
4/24/14

9. Part III: Polarization Film
1) Hold up one polarization film up to the overhead light and rotate around in a circle and record your observations. 2) Hold up two polarization films up to the overhead light and rotate one around in a circle while keeping the other in the same orientation and record your observations. 3) Repeat steps 1 and 2 but use the Smart Board as the light source? 4) Repeat steps 1 and 2 but use the Computer monitor as the light source?

10. Bellwork What is the physics concept behind 3-D movies?
Light Polarization

11. Today’s Agenda
Notes from Yesterday’s Activity
Start the next lab

12. Properties of Light
4/24/14

13. Light and Color Pre-Quiz
Light is a mechanical wave.
All objects emit EM waves.
Light is a particle.
White light is the absence of colors.
Only light has photons.

14. Light and Color Pre-Quiz
Light travels slower in glass then air.
All colors of visible light have the same wavelength.
Radio waves and sound waves are the same type of wave.
Our minds are capable of filling in information that is not there.
The oceans makes our sky appear blue.

15. Light and Color Pre-Quiz
1. Light is a mechanical wave. False 2. All objects emit EM waves. True 3. Light is a particle. Somewhat True 4. White light is the absence of colors.

16. Light and Color Pre-Quiz
5. Only light has photons. False 6. Light travels slower in glass then air. True 7. All colors of visible light have the same wavelength.

17. Light and Color Pre-Quiz
8. Radio waves and sound waves are the same type of wave. False 9. Our minds are capable of filling in information that is not there. True 10. The oceans makes our sky appear blue.

18. Typoglycemia
Can you read the following?

19. I cnduo't bvleiee taht I culod aulaclty uesdtannrd waht I was rdnaieg
I cnduo't bvleiee taht I culod aulaclty uesdtannrd waht I was rdnaieg. Unisg the icndeblire pweor of the hmuan mnid, aocdcrnig to rseecrah at Cmabrigde Uinervtisy, it dseno't mttaer in waht oderr the lterets in a wrod are, the olny irpoamtnt tihng is taht the frsit and lsat ltteer be in the rhgit pclae. The rset can be a taotl mses and you can sitll raed it whoutit a pboerlm. Tihs is bucseae the huamn mnid deos not raed ervey ltteer by istlef, but the wrod as a wlohe. Aaznmig, huh? Yaeh and I awlyas tghhuot slelinpg was ipmorantt! See if yuor fdreins can raed tihs too.

20. Blind Spot Focus on the text or a single letter
Move the closer and farther from you until the black dot disappears

21. What is Light?
Light: is range of EM radiation that can be detected by the human eye.

22. The Photon
Photon: A wave packet (quantum) of an EM radiation (ex. radio, light)
Travel at the speed of light
Have energy
Considered to be both a particle and a wave !

23. Light Transmission
Transmission – the process of EM waves passing through a material

24. Light Transmission
The energy of light transfers energy (vibrations) to electrons
Transparent materials have electrons in the material that match the frequencies of the light (E&M wave)
These photons reemit the light through the material

25. Light Transmission
Light (EM waves) will be absorbed (into heat) if the frequencies do not match.
(page 410)

26. Light Transmission
Transparent: The physical property of allowing EM waves to reemit (pass) through a material
Translucent: Allows diffused EM waves to pass through the material
Opaque: Does not allow EM waves to pass through

27. Light Transmission Plastic film (transparent)
Grocery bag (translucent)
Printer paper (translucent)
Construction paper (opaque)
Black Plastic (opaque)
Aluminum foil (opaque)

28. Light Reflection
Reflection - The turning back of EM waves at a surface.

29. Light Reflection
Metals have free electrons to vibrate and reemit the light
Other materials absorb most of the light without much remission

30. Types of Reflections
Specular reflections – reflect the light in the same forward parallel direction (mirrors)
Diffuse reflections – reflect the light in many different directions
(non glossy paper)

31. Light Reflection Black plastic (mostly specular)
Aluminum foil (somewhat specular)
Plastic film (somewhat specular)
Grocery bag (diffused)
Printer paper (diffused)
Construction paper (diffused)

32. “How do we see objects?” Light has to be emitted from a source
Light is absorbed / transmitted by the object
Light then is reemitted from the object
This is what we see!

33. Light Polarization
Light Polarization: The alignment of EM waves where their electric fields are parallel
Note: This is different from electrical polarization (sticking a balloon to the wall)

34. Light Polarization

35. Light Polarization Lightbulb – Nonpolarized
Projector – Split polarized
Monitor – Polarized

37. Color Making Activity
4/24/14

38. Objective:
To explore the properties of light and color.

39. Materials: Color Maker White Screen
Multi-colored Screens (Red, Green, Blue and Orange)

40. Pre-Lab Questions: (Just answer the questions.)
1) List the colors of the visible spectrum. 2) Is it possible to make white light by using only colored light? Explain why you think this. 3) What color do you think we will get if we mix red and green light on a white screen?

41. Pre-Lab Questions: (Write the questions and answer them.)
4) What color do you think we will get if we mix red, green and blue light on a white screen? 5) Why do you think a banana looks yellow to us in the sunlight? 6) What color do you think an orange would look like in blue light?