If you notice an ambient field can you determine its

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Unformatted text preview: your Hall probe as explained in the Equipment and Software appendices. Before you push any buttons on the computer, locate the magnetic field strength window. You will notice that even when the probe is held away from obvious sources of magnetic fields, such as your bar magnets, you see a non-zero reading. From its behavior determine if this is caused by a real magnetic field or is an electronics artifact or both? If you notice an ambient field, can you determine its cause? Go through the Hall probe calibration procedure outlined in the appendix, or in the Magnetlab Guide Box in the upper right corner of the application. Be sure the sensor amplification switch on the Hall probe is set to 6.4mT range. The MagnetLab application requires the probe to be set to the 6.4mT range to work correctly. Does the Hall probe ever read a zero field? How will you orient the CRT with respect to the coils? Would the deflection be the same if the magnetic field were reversed? Try it. How will you determine the length of the CRT within the magnetic field? Is the field uniform throughout the flight of the electrons? Write down a measurement plan. 163 MAGNETIC FORCE ON A MOVING CHARGE – 1302Lab5Prob8 MEASUREMENT Use the Hall Probe to Measure the magnetic field between the Helmholtz coils. Use the Hall probe to measure the magnitude and direction of the magnetic field between the coils. Measure the field near the coils. Be sure your Hall Probe is calibrated and has the correct orientation to accurately measure the magnetic field. Measure the position of the beam spot for each selected magnetic field. Make at least two measurements for averaging. The voltages listed on the CRT power supplies are approximate, you should check and measure ALL voltages AND currents with a DMM. Read the Equipment appendix if you need to review using a DMM. ANALYSIS Graph your measurements of the deflection of the electron beam for the different values of the magnetic field at a fixed electron speed and compare to your prediction. Repeat for deflection as a function of electron speed for a fixed magnetic field. CONCLUSION How does the deflection of the electron beam depend on the magnetic field? Did your data agree with your prediction? If not, why? What are the limitations on the accuracy of your measurements and analysis? How does the deflection of the electron beam depend on the electron speed? Did your data agree with your prediction? If not, why? What are the limitations on the accuracy of your measurements and analysis? Is controlling the deflection of an electron beam easier with a magnetic field or an electric field? Write down what you mean by easier. 164 CHECK YOUR UNDERSTANDING LAB 5: MAGNETIC FIELDS AND FORCES 1. For each of the configurations of magnets below, sketch the magnetic field map. Assume that the figures do not interact with each other. S N N S S N S N Figure I Figure III Figure II S S N N N S 2. You and your friends are watching an old Godzilla movie. In one scene, a scientist broke a magnet in half because he needed a monopole for his experiment. You cringe and start laughing, but your friends don't understand what you found so funny. Explain the joke. 3. For a cathode ray tube (CRT) with the same electron gun as you used in lab, assume that the distance from the center of the Vx plate to the fluorescent screen is 10 cm, Vacc is 500V and Vx = 6V. The CRT is then placed between the large parallel coils (also used in this lab) which have a current of 1 ampere flowing through them. Assume that the CRT is oriented in the large parallel coils such that the electric field between the Vx plates and the magnetic field are in the same direction. What is the displacement of the electron beam on the screen? This is a difficult problem!! 165 CHECK YOUR UNDERSTANDING LAB 5: MAGNETIC FIELDS AND FORCES 166 TA Name: PHYSICS 1302 LABORATORY REPORT LAB 5: 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 sta...
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This document was uploaded on 02/23/2014 for the course MANAGMENT 2201 at University of Michigan.

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