Physics labs with flavor

1. Physics labs with flavor Agrest Mikhail M. Southern Atlantic Coast Section American Association of Physics Teachers Workshop for Physics and Physical Science Teachers Physics Labs with Flavor Recurrent studies. Physics and Astronomy Department College of Charleston, Charleston, SC Charleston, SC October 23, 2010.

2. Abstract:The principle of recurrent studies as a way to bring flavor into Introductory Physics labs was discussed earlier 1,2. Participants will get some hands-on experience of Recurrent Studies and feel excitement due to the flavor it brings into the introductory Physics Labs You will perform forward study of a phenomenon and calculate unknown parameters based on your own measurements and assumptions. After discussion you will set up the backward study. The purpose of it is to evaluate how accurate was your result in the direct study. Here the parameter of interest in forward study stays unchanged, but others will change. Based on your measurements of some of them and the result of the forward study, you have to predict one (or more) parameters. Then you will perform the backward experiment to measure the value of the predicted parameter and calculate the percent error for your prediction. We expect that you will experience excitement (as students have) and you will be motivated to try the recurrent studies method for innovation of your teaching. 1. M.M. Agrest, “Physics labs with flavor,” Phys. Teach. 47, 297 (May2009) 2. M.M. Agrest, “Physics labs with flavor II,” Phys. Teach. (in print for 2011) Recurrent learning in Physics Labs SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. Physics Labs with Flavor

3. Shoot for your grade Shoot for your grade SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. General Idea • . Forward study • Students study the phenomenon, • perform the experiments, • analyze the data and make conclusions about the results. • find a quantity as a feature of the phenomenon /Based on theoretical model,the measurement results, statistics, etc/ • . Backward study • New assignment; • Based on the results in 1. find the quantity of a questioned parameter. • . Shoot for your grade • Perform the new experiment in the presence of the instructor • Compare the results with the prediction • Get your Grade

4. V0 y-y0 x-x0 M+m V0 M m H Momentum & Energy 1 SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. Kinematics M o m e n t u m a n d E n e r g y I

5. M+m H M+m V0 M m V0 M m H Momentum & Energy 2 SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. M o m e n t u m a n d E n e r g y II Kinematics

6. H h x-x0 Bernoulli SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. Bernoulli's Equation Fluid Mechanics

7. H h H h x-x0 x-x0 Bernoulli2 SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. Fluid Mechanics

8. d Reflection and Refraction SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. Determine Index of Refraction Snell’s Law

9. Total Internal reflection SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies.

10. ## so si f fave 1 2 3 ….. N Focal Length of a Converging Lens SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. Optics Forward study F F Backward study Assignment: Based on your result for the focal length f for a given Sopredict Si

11. # so si f fave 1 2 3 ….. N Focal Length of a diverging Lens SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. Optics F F Backward study Assignment: Based on your result for the focal length f predict Sifor a given So Forward study A

12. Laser y Laser y L L INTERFERENCE SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. Waves of Light

13. Resistors in a circuit V4 V Fig. 1a Fig. 1b R6 R7 R8 R10 R9 V9 V SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. Electricity The forward study.Finding voltage of the power source. Terminals of one of the resistors (let us say resistor R4) in the circuit are accessible, so students can measure the difference of potentials (V4) across this resistor. Based on the measurement of the voltage, students have to calculate the voltage V of the power source. The experiment is repeated several times as follows: Replacing this resistor by a different resistor, students calculate the voltage of the power source several times and estimate the error of their results. Backward study.Finding voltage across the test resistor. The test circuit (Fig.1b) consists of the same power source providing the same value of the voltage as in the forward study to a different circuit. The assignment is: calculate the voltage drop across one of the resistors based on the experimental value of the voltage supplied. The test circuit can be completely different or it can be the same one with the replaced testing resistor. Experimental assessment.Comparing the results. After the “predicted” voltage is announced, the measurement should be performed and the answer is announced. Usually this event attracts students from all other groups of the lab as it is accompanied with shouts “Hurrah”, “Yes!” and other expression of satisfaction. The grade for this part of the lab should be based on the percent error in the predicted value of voltage.

14. Resistors in a circuit V4 V Fig. 1a Fig. 1b R6 R7 R8 R10 R9 V9 V SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. Electricity • Construct a circuit according the diagram 1. • Here: R1=2 kW; R2=6.5 kW; • R3=5.5 kW; R4=1.5 kW; R5=4.5 kW. • Using a voltmeter, measure V4, • based on the measured V4 calculate V of the power source. • Construct a circuit according the diagram 2. • Here: R6=4 kW; R7=3.5 kW; • R8=2.5 kW; R9=5.5 kW; R10=1.5 kW. • Using the calculated value of V from part 1, calculate V9. measure V4, • based on the measured V4 calculate V of the power source.

15. diagram 1 R1 R2 R3 R5 R4 V Resistors in a circuit SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. Electricity diagram 2 Construct a circuit according the diagram 1. Here: R1=2 kW; R2=6.5 kW; R3=5.5 kW; R4=1.5 kW; R5=4.5 kW. Instructor will set the variable power source at Voltage V unknown to you. Using a voltmeter measure V4, based on the measured V4 determine V of the power source. When the same resistors arranged with this power source into another circuit, find voltage drop V4 across its resistor R4

16. Woo...ooo...ooo Waves Speed of Sound in the Air SACS AAPT Physics Labs with Flavor Mikhail M. AgrestFall 2010 Recurrent studies. Assignment 1 Given:Tuning fork with a given frequency f. Find: Speed of Sound in the air. Assignment 2: Result from the Assignment 1: Find frequency of “unknown” (test) tuning fork. Measure: at resonance to find as in (1); Then find Assignment 2Alternative: Use result from the Assignment 1: Set where you expect the resonance based on given frequency f of the test tuning fork. Compare the with one which lets you get the loudest Woo…ooo…ooo

17. The END Visual assessment of students’ prediction of the results emotionally involves them and makes the learning process more effective, brings popularity into the discipline because it involves hands-on experience, using and testing the students’ results during their lab work.