To check whether or not you get the correct behavior

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: nt magnitudes of charge. What range of charge values allows you to accurately measure the length of the electric field vector at all points on the screen? Where is a good place to put the configuration in order to get a larger number of measurements? To check whether or not you get the correct behavior of the electric field from a point charge do the following: 1. Pick a useful charge value and determine several locations at different distances r from the center of the single point charge. (Hint: Choose your locations at regular intervals.) At each location, measure r and the length of the electric field vector. In your notebook, record the data and sketch a plot of the vector length as a function of r. 2. Now, calculate what Coulomb’s law predicts and sketch the values for the field strength vs. distance (r) on the same graph. 3. Compare the shape of the graph to that based on the Coulombs’ law and record your observations. You have to calibrate the computer simulation program in order to translate vector lengths on the screen to vector magnitudes that you calculate using your prediction equation, which are in SI units (assume Q = 1C). You can use the data that you just collected to do this. On the computer, plot the electric field strength in SI units vs. the electric field in length units that you measured with the ruler. Fit a line to the data. If the fit is good, then you can use the fit equation to convert from electric field lengths on the screen to electric field magnitudes in SI units. If it is not good, then you need to go back and repeat steps 1-3 above. Now, explore the line charge configuration. From the sources pull-down menu select 3D Point Charges. Drag positive charges onto the screen to create a long, uniform line of charge. Hints: make sure the charges are evenly distributed. Optimize the overall charge density and placement of the line on the screen in order to be able to obtain good measurements of electric field vectors. Display electric potential values by clicking at the locations of interest for this problem, and investigate how the electric potential depends on position. Determine a measurement plan. MEASUREMENT Measure the electric potential at varying locations along each axis of symmetry. Record the data in your notebook. 51 ELECTRIC POTENTIAL FROM A LINE OF CHARGE – 1302Lab2Prob4 ANALYSIS Use the data for the following analysis (perform on Excel): 1. Using your calibration equation, convert the electric potential values produced by the computer simulation into electric field strengths in SI units. 2. Using your prediction equation, which is based on Coulomb’s law, calculate the expected electric potential in SI units along each axis of symmetry. 3. Compare the calculated potential to that from the computer simulation on a plot for both data sets (2 axes of symmetry). Include uncertainties. Without them, the results are nearly meaningless. CONCLUSION How did your expected result compare to your measured result? Explain any differences. From your results, which general properties of the electric potential does the simulation faithfully reproduce? What is the specific evidence? Where is the electric potential defined to be zero? Is this consistent with your results? Compute the derivative with respect to the distance from the rod along each axis of symmetry. How do these compare with the magnitude of the electric fields from the earlier lab Electric Field from a Line of Charge? Is this consistent with what you know about the relationship between electric field and electric potential? Why or why not? 52 CHECK YOUR UN D ERSTAN D IN G LAB 2: ELECTRIC FIELD S AN D ELECTRIC POTEN TIALS For each of the charge configu rations below , find the electric field and the electric p otential at the p oint m arked w ith the “?”. C onfigu ration 2 C onfigu ration 1 C onfigu ration 4 C onfigu ration 3 53 CHECK YOUR UN D ERSTAN D IN G LAB 2: ELECTRIC FIELD S AN D ELECTRIC POTEN TIALS 54 TA Name: PHYSICS 1302 LABORATORY REPORT LAB 2: Name and ID#: Date performed: Day/Time section meets: Lab Partners' Names: Problem # and Title: Lab Instructor's Initials: Grading Checklist Points LABORATORY JOURNAL: PREDICTIONS (individual predictions and warm-up completed in journal before each lab session) LAB PROCEDURE (measurement plan recorded in journal, tables and graphs made in journal as data is collected, observations written in journal) PROBLEM REPORT:* ORGANIZATION (clear and readable; logical progression from problem statement through conclusions; pictures provided where necessary; correct grammar and spelling; section headings provided; physics stated correctly) DATA AND DATA TABLES (clear and readable; units and assigned uncertainties clearly stated) RESULTS (results clearly indicated; correct, logical, and well-organized calculations with uncertainties indicated; scales, labels and uncertainties on graphs; physics stated correctly) CONCLUSIONS (comparison to prediction & theory discussed with physics stated correctly ; possible sources of uncertainties identified; attention called to experimental problems) TOTAL(incorrect or missing statement of physics will result in a maximum of 60% of the total points achieved; incorrect grammar or spelling will result in a maximum of...
View Full Document

This document was uploaded on 02/23/2014 for the course MANAGMENT 2201 at University of Michigan.

Ask a homework question - tutors are online