Lab212 - Measurements of e-m for an Electron

Lab212 - Measurements of e-m for an Electron - Samuel...

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Lab 212: Measurement of e/m for an Electron Lab 212 Measurements of e/m for an Electron Name : Samuel Dzifanu Objective: The objective of this lab are to measure the charge to mass ratio for an electron and also to examine the situation where the electron's deflected path is due only to its motion in the region of a uniform magnetic field. Theory: In this experiment modeled after Sir Thompson's, electrons originating from a hot cathode are accelerated through a potential difference V established between the cathode and a positive anode or plate. Thus, they acquire a kinetic energy: = eV 12mv2 The electrons then enter an unobstructed volume of the vacuum tube where they are subjected to a magnetic field B oriented perpendicular to the velocity of the particles, given us: = - ( ) F e v x B This force been perpendicular to both the electron velocity and the field accelerates the electrons in a circular orbit: = evB mv2r Diagram: When this electron enters a region where we can apply crossed electric fields as shown in Figure 1, the ratio of e/m can be measured. Procedure:
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This note was uploaded on 09/16/2011 for the course PHYS 121A taught by Professor Opyrchal during the Spring '11 term at NJIT.

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Lab212 - Measurements of e-m for an Electron - Samuel...

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