Wednesday, Feb 11, 2009 - Block 4B

Had students take out planners and write in them that there is a test on waves on Friday.

Students took out notebooks.
Gave students 3 minutes to list every demo and lab, no matter how big or small, we did about waves. Asked how many students had 10 or more, 8 or more, 5 or more, at least 2.

Went around the room asking for the demos and labs and then what the main idea behind it was.
1. Slinky lab - create transverse and longitudinal waves, show the relationships between energy, frequency, and wavelength, show standing waves with nodes and antinodes.
2. Oscilloscope lab with frequency generator - show that high pitch waves have high frequency and short wavelengths
3. Oscilloscope lab with microphone - students talk or whistle into microphone. See "voice prints". Again see that high frequency and high pitch sounds have short wavelengths
4. Singing rods - the shorter rods created shorter wavelength, higher pitched sounds
5. Gong Grates - sound travels at different speeds in different materials
6. Thunder Tube - Speed of sound. You see a flash of lightning and then count the seconds until you hear the thunder. 5 seconds for every mile away.
7. People waves - show difference between transverse and longitudinal waves
8. Student leaves room - diffraction - you can hear around corners but not see around corners because the longer wavelength sound waves are bent (diffracted) more
9. Pencil in water - refraction - light is bent when it goes from one medium into another due to differences in wave speed.
10. Mirror - reflection - angle of incoming wave = angle of outgoing wave
11. Belly dancing tuning fork - waves are caused by vibrations. A wave is a wiggle that moves through space. Also see nodes and antinodes.
12. Straw Duck Calls - longer straws create longer wavelengths and lower pitch
13. Pull-a-tune - the longer bars created longer wavelength, lower pitched sounds

Went over RA 11.2a, RA 11.2b
Gave out Wave Vocab matching exercise and Wave Crossword for review.