Physics II Studio
Major Experiment #3
Spring Term 2013
The third major experiment to be performed for the class will take place in BL114 on Wednesday, May 2, 2013. The experiment that will be performed is entitled "Capacitance", a description of which begins on page 4-16.
Your tasks will be to determine the capacitance of three capacitors using a constant current source and constant voltage source. You will also evaluate the model for the capacitance of (at least) two capacitors connected in parallel, not series like the manual says!
Please make sure you discharge the capacitors with a wire and NOT your laptop (unless you hate it and want to see it smoke!). Discharge the capacitors before you connect your lap top to the circuit.
Please save all of your data files (the lab manual tells you not to, but I want you to). Make sure you record the filenames and extensions in your procedure section. Include four graphs, one sample for charging a capacitor and one for discharging a capacitor to be placed in the Procedure Section. Neither curve should have curve fits on it. In the Analysis Section, place one graph for charging a capacitor with curve fit and one graph for discharging a capacitor with curve fit. Also in the Analysis section, list the filename and extension and list the data that you found from the respective curve fit.
Remember, for the constant current source (charging the capacitor), fit a line to the inclined part; do NOT include any horizontal parts. For the constant voltage source (discharging the capacitor), fit a natural exponent to the curved part only (again, not straight, horizontal lines). Look at the coefficient of the natural exponent, C. This is NOT the capacitance or the amount of charge, but equal to 1/RC. R is the resistance in the circuit and C is the capacitance. It looks odd, but you set 1/RC equal to the C from Logger Pro and solve for the C in the equation.
Before you leave lab, make sure that you have measured each capacitor two ways and made a parallel connection of at least two capacitors and measured it two ways.
The lab reports are due Friday, May 10, 2013 by 5:30 PM in the green bin outside my office.
Lab Report Format
A complete lab report must have the following sections:
Do not forget to update your Table of Contents and to number the pages in your lab notebook!
The first page of your report must have a title, the name of the P.I. (explicitly indicate who was the P.I.), the name of the lab assistant, and the date that the report was turned in (not the date that you performed the experiment!).
*Abstract - a BRIEF description of what you were investigating, how you conducted the experiment and your conclusions based on your experience. The abstract should not be a discussion of what you are going to do in the lab. The abstract cannot be written before you have analyzed your data. In the lab notebook, skip a page or two so that you can write this in at the beginning of the report after you have analyzed your data.
Introduction - a discussion about any details that you think would help someone perform the experiment. This should include a discussion about the model or the method selected for performing the tests. If you use models (equations) in your analysis, list the models in this section and describe what each of the variables represent.
**Procedure - a detailed description of what you did in the lab. At the beginning of this section, place the date and the time that you began the experiment. This section must include a schematic, detailing how things were connected, where appropriate. The raw data must appear in this section immediately following the description about how the data was taken. A person must be able to read your procedure section and be able to duplicate your results without having the lab manual present. Do not do any calculations in this section, just record how you performed the experiments and record the raw data. If the data is taken by computer, you must specify the path and filename where the data is stored. This information must be listed in this section right after the description of how the data was taken. Do not simply list all of the files generated at the end of the section.
This section be signed by the instructor before you leave the lab. If you turn in a report without the signature, it will not be accepted!
Analysis - a sample of the calculations made in the lab. This section should include a sample of the error calculations and propagation of errors used in your analysis. The final data that you are analyzing to generate conclusions, the values with appropriate uncertainties, must be shown in this section. The actual calculations for each one does not have to be included, as long as you show an example for one, but you may include them all if you wish. The calculations may be done by the computer, but include printouts of the worksheet in your lab book. Any graphs or printouts that are placed in your notebook must occupy one whole page and be trimmed to fit within the page and not hang outside of the notebook.
*Conclusion - this section must have a conclusion that is based on your experiments and analysis. If your conclusions do not following logically from your analysis, your grade will be deducted significantly. This section must also contain a brief description of significant factors that you think affected your data, in particular, the uncertainties in your data (factors that contributed to the error in your experiment). A good thing to keep in mind is to think of this report as a report you are submitting as part of your job responsibilities. If you do not think your boss would accept what you have to say, it is a safe bet that I will not like it either.
The asterisks indicate the sections that I will pay closest attention to.
Modified May 02, 2013 by Galen C. Duree Jr.