Physics III Lab
Spring Term 2016
Instructor: Galen C. Duree Jr., PhD
Office: Room CL105 Phone: 872-6025 Box: 182
Office Hours: 9:15 AM - 10:15 AM M T Th & 4:20 PM - 5:30 PM M T F
The third lab experiments, entitled "Lenses", a description of which begins on page 154 in the lab manual, were conducted in CL117 on Friday, April 22, 2016, starting at 8:05 AM.
The lab reports are due in the green bin outside the PHOE department office by 5:30 PM on Friday, April 29, 2016.
For this lab, follow the procedure listed in the manual. There are essentially two tasks that you need to do: (1) determine the focal length of lenses A, B, and C; (2) Evaluate the theoretical expressions for the magnification of a lens and a simple telescope. You may estimate the uncertainty on the distances by changing the positions until you can definitely tell that the image quality has changed. For each lens, get at least 3 different sets of image/object distances. Find the focal length for each set and then compute the average and standard deviation for the focal length. For your magnification calculations, make sure that you include the uncertainty. If you are not sure about how to do this, please ask! Do not forget to do steps 6 and 7 - two different types of telescopes.
From the previous lab:
For this lab (Faraday's Law), you will be evaluating a couple of induction models for the given coil arrangement. The first model is the induced emf is proportional to ΔV/Δt for a saw-tooth input function. Take data for at least 7 different values of ΔV/Δt. The uncertainty in the induced emf should be estimated from the readings on your oscilloscope. Before you make the graph for this situation, make sure that you propagate the uncertainty for the ΔV/Δt values since you should have an uncertainty with ΔV and a separate one for Δt. Make a graph of induced emf vs. ΔV/Δt, fit a trend line to the data and place error bars on all of the points. If a majority of the points' error bars cross the trend line, the model is appropriate; if they do not, then the model is not appropriate for your situation.
The second model is the induced emf is proportional to the angular frequency for a sinusoidal input function. Take data of the induced emf for at least 7 different values of frequency. Calculate the angular frequencies and determine the appropriate uncertainties. Make a graph of induced emf vs. linear frequency (f) OR angular frequency (ω), fit a trend line to the data and place error bars on all of the points. If a majority of the points' error bars cross the trend line, the model is appropriate; if they do not, then the model is not appropriate for your situation.
Download a copy of the Error Analysis Worksheet
The third series of experiments are entitled "Lenses" and will be conducted on April 22, 2016.
Lab Report Format
A complete lab report must have the following sections:
Make sure that you address the specific tasks that I give you! If you perform great analysis and have insightful conclusions, but do not address the tasks that I give you, do NOT expect a very good grade on your report - no matter how much effort you put into it!
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. Try to write the abstract with 150 words or less, but still communicate important information. 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. Do NOT include formulas for calculating averages and standard deviations.
*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 particular attention to when grading.
Modified April 28, 2016 by Galen C. Duree Jr.