Handed out sheet of paper and gave "quiz"
1. What is going right in this class?
2. What is not going well?
3. How can this class be improved?
4. Is there too much homework?
5. Why aren't you handing in homework?
6. Should the homework be graded? How would you like to be assessed in this class?
7. Other comments.
I will give credit for the quiz since I want to know how to make the course better.
Check out www.quia.com/report/rholmes100 and do the physical science activities on wave vocabulary. Write-up and email dated class notes to me on waves so I can update my blog accurately.
Explained that when I grade labs I punch the data into an Excel spreadsheet. Students NEED to include ALL raw data in their data tables. If they do, I should get the same answers that they do.
If students are dealing with uncertainties, they need to explain how they came up with them.
Students should also have the same data as their partners.
I then handed out a worksheet review on waves and allowed students to either work on that or work on their pendulum labs.
The test is delayed until Wed or Thurs.
Monday, March 9, 2009
Friday, March 6, 2009
Thursday, Mar 5, 2009 - Block 3
Students did the Pendulum lab.
This is a lab that will be sent to IB and should include a well-written design section, data collection and presentation section with uncertainties, and a complete results section including a discussion of the procedure and ways to improve the lab.
Most students used Vernier photogates or motion sensors.
This is a lab that will be sent to IB and should include a well-written design section, data collection and presentation section with uncertainties, and a complete results section including a discussion of the procedure and ways to improve the lab.
Most students used Vernier photogates or motion sensors.
Wed March 4, 2009 - Block 3
Went over RA 18.1, 18.2
Some students were having difficulty with superposition so I gave out the Hewitt concept development sheet on superposition as practice.
Went over single slit diffraction and showed how to find the minima.
Showed how to use this for resolution problems. You can resolve two objects if they are far enough apart that the central maximum for one source falls in the first minimum for the second.
Some students were having difficulty with superposition so I gave out the Hewitt concept development sheet on superposition as practice.
Went over single slit diffraction and showed how to find the minima.
Showed how to use this for resolution problems. You can resolve two objects if they are far enough apart that the central maximum for one source falls in the first minimum for the second.
Tues, Mar 3, 2009 - Block 3
Polarization
Demos of polarizers.
Only transverse waves can be polarized. Demo with telephone cord and picket fence.
Showed how to calculate the intensity. The intensity is proportional to the square of the amplitude.
Went through some examples with polarizers at different angles and calculated the intensity.
Went outside and used polarizers to view the sky. Light can be polarized by scattering. Also viewed glare showing the light can be polarized by reflection.
Back inside, showed why light is polarized by scattering.
Discussed possible lab on factors that affect polarization by reflection.
Demos of polarizers.
Only transverse waves can be polarized. Demo with telephone cord and picket fence.
Showed how to calculate the intensity. The intensity is proportional to the square of the amplitude.
Went through some examples with polarizers at different angles and calculated the intensity.
Went outside and used polarizers to view the sky. Light can be polarized by scattering. Also viewed glare showing the light can be polarized by reflection.
Back inside, showed why light is polarized by scattering.
Discussed possible lab on factors that affect polarization by reflection.
Monday, Mar 2, 2009 - Block 3
Doppler Effect
Derived equations for frequency for both moving source and moving receiver using the relative velocity equation.
Did several examples on the board.
Showed pictures of Doppler Effect for light and how it can be used in astronomy (rotation of Andromeda Galaxy, binary star systems)
Derived equations for frequency for both moving source and moving receiver using the relative velocity equation.
Did several examples on the board.
Showed pictures of Doppler Effect for light and how it can be used in astronomy (rotation of Andromeda Galaxy, binary star systems)
Friday, Feb 27, 2009 - Block 3
Discussed standing waves. Showed examples for open and closed pipes and waves on a string.
Calculated lengths of closed tube that would give resonances.
Demo/Lab on resonance in a pipe. Compared experimental values to calculated values.
Wave on a string lab/demo: Calculated the speed of the wave on the spring.
Calculated lengths of closed tube that would give resonances.
Demo/Lab on resonance in a pipe. Compared experimental values to calculated values.
Wave on a string lab/demo: Calculated the speed of the wave on the spring.
Thursday, February 26, 2009
Thursday, Feb 26, 2009
Reviewed reflection and refraction.
Asked what value students got for the index of refraction of light in water. Used this value to calculate the speed of light in water.
Showed again that when going from fast to slow the wave bends towards the normal. When going from slow to fast, the wave bends away from the normal.
In going from slow to fast, as you increase the angle of incidence, you reach a point where the angle of diffraction is 90 deg. If you increase the angle of incidence any more, you do not get a refracted ray, instead you get total internal reflection. Demonstrated total internal refraction with laser and optic fiber.
Defined and calculated the critical angle.
Other examples of refraction are mirages and the fact that the Sun is already really well below the horizon when you see it setting.
Talked about diffraction - bending or spreading of a wave as it passes through an opening or around a barrier. Sent student out into hallway. They can hear you but not see you. Calculated the wavelength of the sound wave and compared it to the wavelength of light. Longer wavelengths are diffracted more. That is why you can hear around corners but not see around corners.
Used circular pattern overheads to demonstrated diffraction and interference.
Young's double slit diffraction experiment was used to measure the wavelength of light. Described the set-up and math for the experiment.
We used a double slit to measure the wavelength of laser light.
I then showed how to measure the wavelength using a ruler. We got a value of 590 nm.
Handed out worksheet on reflection and refraction.
Asked what value students got for the index of refraction of light in water. Used this value to calculate the speed of light in water.
Showed again that when going from fast to slow the wave bends towards the normal. When going from slow to fast, the wave bends away from the normal.
In going from slow to fast, as you increase the angle of incidence, you reach a point where the angle of diffraction is 90 deg. If you increase the angle of incidence any more, you do not get a refracted ray, instead you get total internal reflection. Demonstrated total internal refraction with laser and optic fiber.
Defined and calculated the critical angle.
Other examples of refraction are mirages and the fact that the Sun is already really well below the horizon when you see it setting.
Talked about diffraction - bending or spreading of a wave as it passes through an opening or around a barrier. Sent student out into hallway. They can hear you but not see you. Calculated the wavelength of the sound wave and compared it to the wavelength of light. Longer wavelengths are diffracted more. That is why you can hear around corners but not see around corners.
Used circular pattern overheads to demonstrated diffraction and interference.
Young's double slit diffraction experiment was used to measure the wavelength of light. Described the set-up and math for the experiment.
We used a double slit to measure the wavelength of laser light.
I then showed how to measure the wavelength using a ruler. We got a value of 590 nm.
Handed out worksheet on reflection and refraction.
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