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Unformatted text preview: Physics 241 Formal Report Name: Sean Thornton Partner: James Mo GSI: Tony Smith Section: 144 Formal Report set in L A T E X2 1 Introduction: The main purpose of this lab is to help us study the properties of electrons and ultimately determine the charge-to-mass ratio of an electron. We will be examining the motion of charged particles under an electric field and under an electric field. This in turn, will allow us to learn by the end of the lab how to predict the path of a charged particle in a constant magnetic or electric field. Lastly, we will understand both systematic and statistical error and how they affect our experimental results. In this lab, the most important equipment vital to our experiment will be the deflection tube (Tel Atomic TEL 525), the Helmholtz coils, and the three different power supplies. The deflection tube will allow us to emit cathode rays (electrons) inside of an evacuated glass tube. This emission can be bent under the influence of either a magnetic or an electric field. The Helmholtz coils will provide us with a relatively uniform magnetic field in the center of the deflection tube. Finally, our three different power supplies will allow us to run several different experiments to help us determine the charge-to-mass ratio of an electron. The Extech power supply will supply a current to the Helmholtz coils in order to create a uniform magnetic field; the UMHVPS will provide a voltage across our deflection plates inside of the deflection tube; the TEL 2813 supply will control the potential difference of the deflection tube which in essence, controls the acceleraton of the electrons before they are projected across the mica sheet. Section 6.3.1 - Magnetic Deflection Objective To observe the change in trajectory of an electron beam when it is subjected to a magnetic field perpendicular to its path of movement. This section also allows us to make a connection between the force on the charged particles and their radius of curvature to the magnetic field at varying voltages (including both positive and negative deflection). This allows us to conclude that charged particles can be influenced by a magnetic field and also allows us to derive a rough estimate of the charge-to-mass ratio of the particle. Procedure We did not deviate in any way from the methods outlined in the Physics 241 lab manual.However I would like to note that in recording our data, we came across a problem in our work sheet because we did not know how to make the electron beam deflect up instead of down. Thinking about this, we realized that in order to reverse the direction of the magnetic field for a positive deflection of the electrons, we needed to reverse the direction of the current!...
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This note was uploaded on 12/28/2010 for the course PHYSICS 241 taught by Professor Gidley during the Winter '09 term at University of Michigan.
- Winter '09