Week 4 Jan 27th

• Data is being taken currently for Schawlow.
• I'll continue to discuss
• We had some extra time built into this lab, and per the dangerous deep snow days---we are OK
• You should be signed up for data taking or doing it.
  • Sign uu
  • Plans for done with Data are for Wed. Jan 29. We can stretch to end of the week, but be on top of it.
  • We should be signing up for one on one times
    • Know how to align, take measurements and do a small angle calculation to determine wavelength (small angle approx is quick if you have it in your lab notebook).
    • You should follow how you derive that small angle approx from path difference fomula.
    • This will be markerboard work after you measure
    • Have your lab notebook prepped with what you need to find wavelength from the measurements.
• Schawlow was our look at spectroscopy by using a diffraction grating
  • We will use a real much more finely tuned instrument to do spectroscopy later---and will get wavelength to about 0.05nm.
  • That will use a monochromator---first we looked at division of wavefront, then we use it.
• Michelson--be looking ahead
  • This is division of amplitude (part of wave goes one path, the rest takes another path)----- "There's a difference between knowing the path and walking the path"
  • We will do some real spectroscopy with this
    • First you will count fringes to determine wavelength (better way of counting is welcome---project ideas)
    • You will then count washout patterns to determine spacing between sodium lines
    • You will then find white light fringes (this is a subtle skill---When you can take this grasshopper from my hand, you will have mastered the five point palm exploding heart technique)[ figure that mixed quote out]
    • Your hands on evaluation will be to start from messed up Michelson, and then find white light fringes (less than 30 minutes). "We did it"!!!!
  • I have several resources posted to help you with Michelson
• I am currently grading/reading final drafts on speed of light (not done yet).
• Some general comments on writing
  • "To be" has no place in your lab writeups. You shall strive to be ommiting "to be" or other passive voice uses.
  • "I measure", "We do", "We determined". "The measurement is made"......Active voice please, is to be what you must strive to be using (I mean, Use active voice. It is direct).
  • "our laser" "our oscilloscope". No need to be possesive. It is the scope used and has critical specifications you have described.
  • I look for reasons for information you decide to give me. I trust that if you give me r^2 in a fit, that you intend to with good reason and that it means something (I trust you). When I find no mention of the number after diligently looking............
  • If you give me information, please give the reason I am looking at that. "It was the please that caught my memory". https://www.getyarn.io/yarn-clip/be028ab7-d15d-4dbd-9e4e-3bdada331b93
  • Many of my comments are style (though many are requirements). Style comments---I try to convey how I am reading your work and asking if you intended that interpretation.
  • Sig figs, uncertainties, and final results.
    • c=number + - number units. The uncertainty is often kept to one sig fig, sometimes a second (unless you have done the done a more rigorous statistical analysis from a large data set). This means you cannot go beyond that decimal place in your answer that says ---"I only know numbers out to this digit".
  • Usually T is used for a time period that is repeated, where "t" is used to denote the variable "time", rather than some constant T.
  • Rather than tell me equipment model (which is OK to do), it is more significant to tell me the critical specifications that are needed. (HeNe--long tube, why, how long--Scope fast--how fast, why, ---detectors fast, how fast, why).
• You are all doing great. Keep up the good work. https://youtu.be/lcE1u2fAkRY?si=xfW_BqNZQAilfU-n
• If it is movie quotes, I can out bumblebee bumblebee----https://youtu.be/iE0yPfstcp0?si=dp6bbM7RkQqIiuLv