Modern Optics Lab Introductory Meeting Modern Optics Lab Contact Information Lab Organization: Gernot Laicher South Physics 410 (801) 585-5553 [email protected] Teaching Assistants: Prof. Tho Nguyen (Thursday and Friday Sections) [email protected] Fei Teng (Tuesday and Wednesday Sections) [email protected] Website: http://www.physics.utah.edu/~gernot/Modern Optics/Modern Optics.html Modern Optics Lab Lab Format Lab descriptions will be on our website (pdf files).
Before the lab: * Read through lab description. * Try to understand the principle of the experiment and the evaluation methods. * Think about the format of your lab report. data Labs are done individually, not in groups. A short introduction/overview to the lab activity is usually given at the beginning of the lab. Lab report is written during the lab activity and submitted at the end of the 4 hour lab period. 12 labs are planned over the course of the class (may vary). Modern Optics Lab Grading in Modern Optics
Quizzes: 15% Midterm Exams: 20% Final Exam: 30% Lab Grade: 35% Your lab score is obtained as follows: 90%: Grade received for lab reports 10%: General Lab conduct - Displayed interest/diligence in lab activity - Ability to answer questions asked by TA - Cleanliness of workspace at the end of the lab - Creativity - Punctuality Modern Optics Lab Guidelines for Writing the Lab Report Keep in mind the main purpose of a lab report which is a written record of the a) purpose of the lab activity, b) methods and techniques - experimentally and mathematically,
c) raw data as measured and their uncertainties, d) data analysis (e.g., computations) including error propagation, e) conclusions derived from your data analysis. Say what needs to be said as efficiently, concise, and clear as possible we are not writing novels. A picture is worth a thousand words: Include a sketch of the apparatus when describing the methods. Label whats on the sketch. Dont forget units ! Dont submit messy lab reports in which the TA needs to fish for information.
Modern Optics Lab Lab Report Grading General guideline (may vary somewhat depending on lab activity and TA): 20% Purpose, Methods, Techniques .. 30% Raw Data Record 20% Data Analysis 10% Error calculation - Measurement uncertainties in raw data - Propagation of error 20% General appearance and organization - Legible ? - Looks organized ? - Easy to follow ? Modern Optics Lab Extra Lab Time If you run out of time before completing the lab: Talk to the TA, see whether he can arrange extra lab
time on T,W,H, or F (Mondays generally not available) to complete an activity. For up to two lab activities extra time may be granted (no guarantee). Extra time Automatic 15% reduction in lab report grade (exception: illness, etc.). Modern Optics Lab Lab Report Deadlines 1) 2) Submit at the end of lab period, if possible. Deadlines: Tuesday section: Wednesday by 5 p.m. Wednesday section: Thursday by 5 p.m. Thursday section: Friday by 5 p.m. Friday section: Mondays by 1:45 p.m. (just before the lecture) 3) Lab reports turned in after the deadline described above will have credit deducted as follows: 10% off for every extra day late *. Example: A lab report from a Tuesday section that is not turned in by Wednesday at 5 p.m. but is instead turned in on Friday at 3 p.m. will have a 20% penalty
deducted. So, if a student would have gotten a 68% score, the adjusted score will be 68%*0.8=54.4%. *For the Friday section: Lab reports turned in later than Mondays 1:15 p.m. will immediately start with a 20% late penalty and increment by 10% every day at 10 a.m.. That is because the Friday section already has an extra 1.8 days over the weekend.* Modern Optics Lab Lab Report Deadlines 4) Reports turned into the TAs mailbox (JFB 220 for Fei Teng and JFB 201 for Prof. Nguyen): Have the lab report dated and signed by the secretary in JFB 201 before putting it in the TAs mailbox. Unsigned/undated reports: TA will assume that the report was turned in 5 minutes before the mailbox was emptied by the TA. 5) If a student makes up a missed lab due to illness, etc., the deadline for the lab report is accordingly the day after he/she makes up that lab activity. 6)If extra lab time is granted: Turn in the lab report at 1 day after the extra lab time is performed (5pm or 1:45pm on Mondays). Automatic15% deduction for extra lab time still applies.
Modern Optics Lab Missing a lab due to Illness, etc. Arrange with the TA a way to make up the missed lab activity. - If possible, in another section the same week. - Alternatively a time outside the regular lab hours may be arranged between you and TA. - Worst case: We may waive a lab and base your grade on the remaining average. You cannot expect to be allowed to make up a lab activity without penalty unless you have a very good reason (illness, etc.). Modern Optics Lab Sample Lab Report Pages Modern Optics Lab Significant Figures and Uncertainty Report uncertainties (error) in measurements to one significant digit
Make sure the position of the least significant digit of the measured value agrees with that of the uncertainty. x 5.8 0.4 cm Modern Optics Lab Estimating and Reporting Uncertainty Estimation of uncertainty from a single measurement due to measuring device (e.g., ability to read out a scale) Uncertainty in repeated measurements and averaging (averaging 5 or more measurements to get mean) calculate standard deviation of the mean x x N x Standard deviation of the mean
x Standard deviation Modern Optics Lab Error Propagation Calculating the error in the final result based on the error in the measured quantity can be done in several ways. a) Calculate the high and low possible outcome based on using extreme values of input data (x+x and x-x). b) Doing a proper error calculation. Modern Optics Lab High/Low Method Suppose you measure a quantity and its uncertainty xo xo .and you want to calculate the value of a function f(x) and the uncertainty f of the function f(x) at the point x=xo
f x x 2 xo 2.5 0.3 Modern Optics Lab 15 f(x)=x^2 10 f(x) f xo xo f xo 5 f xo xo 0
0 1 2 xo xo Modern Optics Lab xo 3 xo xo x 4 2 f xo f ' xo f xo f ' xo xo 2 xo 15
f ' xo xo 2 f(x)=x^2 10 f xo xo f(x) f xo f ' xo 2 f xo 5 f xo xo 0 0 1 2
xo 2 xo Modern Optics Lab 3 x 4 General Error Propagation Method f x ........ df f ( x ) x dx 2 f x, y, z...... ........ 2
2 2 f f f f ( x, y, z...) x y z ... x y z Modern Optics Lab Example n1 sin 1 n2 sin 2 n1 1.52 0.03 n2 1 34.2 0.4 n1 sin 1 1.52 sin 34.2 1.8565.....
sin 2 sin 27.4 2 27.4 0.6 2 2 n n n n2 2 n1 2 1 2 2 n1 1 2 2 n2 sin 1 sin 34.2
1.221 n1 sin 2 sin 27.4 n2 n1 cos 1 1.52 cos 34.2 2.732 1 sin 2 sin 27.4 n2 n1 sin 1 1.52 sin 34.2 2 cos 2 cos 27.4 3.582 2 2 sin 2 sin 27.4 Modern Optics Lab Example n1 sin 1 n2 sin 2 n1 1.52 0.03
n2 1 34.2 0.4 n1 sin 1 1.52 sin 34.2 1.8565..... sin 2 sin 27.4 2 27.4 0.6 2 n2 1.2210.03 2.732 0.4 3 . 582
0 . 6 180 180 0.056 2 n2 1.86 .06 Modern Optics Lab
2 Example using High/Low Method n1 sin 1 n2 sin 2 n1 1.52 0.03 1 34.2 0.4 2 27.4 0.6 n1 n1 sin 1 1 1.55 sin 34.6 n2,max 1.952.... sin 2 2 sin 26.8 n n1 sin 1 1 1.49 sin 33.8 1.766.... n2,min 1 sin 2 2 sin 28.0 n2 n2,max n2,min 2
1.952 1.766 0.09 2 n2 1.86 .09 Modern Optics Lab Method overestimates error somewhat
