Lab 10 Prep

First a note on Lab 9X.  All I can say is "Wow!"  We got organized and got that done really efficiently. Things to note:  good prep really helps.  Good planning really helps.  Good organization really helps.  Good communication really helps.  And a clock tick can help too.  (But don't be a slave to it).  What really makes it work though is good teaming.  

Each team please asap email me your data from the experiments done Monday in lab; I will post them on the blog along with the error term analyses and procedure updates.  Analyzing the data is optional.

Lab 10 Prep Pkg (PDF File)

There are no briefing materials for Lab 10.  We will be discussing image formation and optical systems, working with telescope optics on the table, and learning cleaning techniques under the hood.

Lab 9X Prep

Lab 9X will finish off Lab 9, which is too long to do in a single session.  For the prep you will need to work in your 3 groups to come to consensus on your work product.  These are what we discussed in class on Wednesday.  Each team will need to email me pdf's of the two work products before lab.  Each team please also bring 4 hard copies.  One of these copies will be used in the briefing via the overhead projector camera and the remaining three will be distributed among the teams.

Team Mercury:

1)  Determine your team's best value for the error introduced by background light and its drifts.  You will have 2 parts to your analysis:  one regarding the background drifts, and another that explicitly considers the background contribution to the signal in the measurement of I(theta).  You can use any reasonable units you wish as long as they are quantitative.  Generate a 1-page pdf describing how the error values were estimated, and report the values.

2)  Generate a procedure to minimize the errors due to background light in an improved version of Lab 8's Malus' Law experiment.  Generate a 1-page pdf describing this procedure adequate for sharing with the class

Team Gemini

1) Determine your team's best value for the errors introduced by human factors.  You can use any reasonable units as long as they are quantititive.  Generate a 1-page pdf describing how the values were estimated, and report the values.  

2)  Generate a procedure to minimize the errors due to human factors in an improved version of Lab 8's Malus' Law experiment.  Generate a 1-page pdf describing this procedure adequate for sharing with the class.

 

Team Apollo:  

1)  Determine your team's best value for the error introduced by laser drifts.  You can use any reasonable units you wish as long as they are quantitative.  Generate a 1-page pdf describing how the value was estimated, and report the value.  

2)  Generate a procedure to minimize the laser drift error in an improved version of Lab 8's Malus' Law experiment.  Generate a 1-page pdf describing this procedure adequate for sharing with the class.

Lab 9 Materials Available

Lab 9 Prep Package (PDF File)
Lab 9 Briefing Materials (PDF File)
Sample Lab 8 Data for inspection/reference (PDF from Google Spreadsheet)


Lab 9 will build on the good success of 8X.  Here we are adding the idea of an error budget to the idea of an experiment design.  An error budget considers all of the effects that lead to uncertainty in an experiment's results.  By estimating each effect and rolling them all up into a total error you have a good idea of the quality of results you can expect.  An error budget is also a good debugging tool.  If you see more error than expected in a measurement, you can check each term in the error budget to see where either an assumption is wrong or the apparatus is misbehaving.  This provides a systematic way for you make corrections.

Lab 8 Wrap Up / Lab 8X Prep

Lab 8 is one of my favorite labs.  It's where the rubber really meets the road in terms of an experiment, and where the teams really need to work together to get the work done efficiently.  This year the teams are bigger, but you all rose to the challenge and organized yourselves quickly.  It's too bad we don't have a couple of extra radiometers and rotating polarizers - things would go faster and the teams could be smaller for this experiment.

Three things are just plain true that slow us down a little compared to last time the class was taught.  First, we have more people in the class.  Another is that the classroom is in another building from the lab so we have to spend 5-10 minutes in transit.  And finally, we start half an hour later, and folks still want to get home at a reasonable time, so the open lab time is shorter.

And so we didn't quite finish.  Another half-hour would have done it.  We'll wrap it up next time, starting with 8E and moving to 8F.  We'll call this combo Lab 8X (for 8-extended).

For Lab 8X prep, complete the following tasks:

1.  Make sure your data for experiment 8A-8D is complete and recorded in the proper format.
2.  Write down at least 3 good questions you have about the experiment or your data.
3.  Compute how many laser photons at a time were in your polarizing filter.  Record explicitly any assumptions you needed to make.
4.  Enumerate the 6 mechanical degrees of freedom (three coordinates and 3 angles) of the polarizer in its mount and how those degrees of freedom are made repeatable each time when the mount is blocked on the table.

A polarizer in its mount blocked on the table with 3 bolts

The other polarizer on the table, but unblocked

Finally, the lab will be open 5-6 PM this coming Monday, October 22, with the table set up for Lab 8.

Lab 8 - Quantitative Polarization Prep & Materials

Lab 8 Prep Package (PDF file)

Lab 8 Briefing Materials (PDF file)

Prep involves watching a video lecture where Walter Lewin describes Malus' Law, the topic of our lab.  There are now a huge number of physics lectures on-line.  These are an incredible resource for learning.

Lab 7 Prep and Materials

Lab 7 Prep Package (PDF File)

Lab 7 Briefing Material (PDF File)

Bring some small transparent items.
We will meet in the classroom first, then move over to the lab.

Lab 6 - Retrospective on Lab Notebooks

In lab 6 I spent 5-10 minutes one-on-one going over lab notebooks. These were good discussions.  Some comments:

1. There is a wide range in style.
2. Several students are using electronic notebooks.  Some of these are local applications and some are in the cloud.  If yours is a local application be sure to back up the content!. There is a wide range in notebook quality.
4. Not everyone seemed satisfied with their notebooks.
5. Here's a strategy for improving your notebook:
--- Refer to the checklist in the material for Lab 1.
--- Review your notebook against the checklist.
--- Pick an area to improve.
--- Spend extra effort on that area until you see improvement.
--- Iterate.
6. Some notebooks didn't record lab procedures. These are necessary to reproduce a result.  Imagine you will be handing your notebook to a colleague who will use your notes to re-do an experiment.
7. Good notebooks can save you in the future from extra work redoing stuff that you just didn't bother to record. Get in the habit of recording a little more than you think you need to.
8. When something is puzzling, make a note of it in your notebook.  A puzzle is meant to be solved.  Solving puzzles yields understanding.  You should not just let an inconsistent result stand without tracking it down or at least making an obvious note of it.

Except for those of you to whom I gave a "bye" for further rounds, I will review lab notebooks in class again. At that time we will make "improvement contracts". In the meantime, use the feedback provided and these comments as an opportunity to improve your practices. Out in the wild you will find it necessary to keep good lab records in order to make reliable progress on a project and be confident of the results.

Lab 6 Briefing

Meet in the lab, Wing B 144, instead of the classroom.

Hard to believe we're already finishing week 3. That means it's time for lab notebook review, so prep this time is to catch your lab notebook up-to-date and be prepared to show it to me during the next lab session. I'll spend 5 or so minutes with each of you assessing notebook quality. There will be 2 possible outcomes:  (1) you've got an acceptable notebook and you're good to go - you've got a pass on further notebook review. And (2), I'll be reviewing your notebook again to see how you are improving based on the advice I give you. Notebook quality is not directly a part of your grade, it only counts so far as good notebook quality helps you otherwise get a good grade. So treat this as a no-risk skill-building exercise. Good lab notebooks are essential - without good notes all you are doing is experiencing.  Without records you can not really do science since a key aspect of science is it's repeatability.

Lab 5 Briefing Materials Available

Lab 5 - Interference Fringes (PDF File)
Lab Self-Assessment Rev 2 (PDF File)

Lab 5 Prep Package Available

Lab 5 Prep Package (PDF File)

... in which you explore small angles, analyze Lab 4's data and design a small part for an experiment.

Lab 4 Materials Available

Lab 4 Prep Package (PDF File)
Lab 4 - Cornell Plates Briefing (PDF File)

Lab 4 - centimeter / millimeter scale (PDF File)