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Unformatted text preview: also record the accelerating voltage. Next align the electron beam with its reflection to measure the radius of the electron beam. Data Current to Helmholtz coils (I)= 1.44A Accelerating voltage (V)= 183.6 Electron beam radius (r)= 4 Calculations The equation used to find the e/m: e/m=v/Br=2V(5/4) 2 a 2 /(N Ir) 2 N is the number of loop in the coils: 130 a is 15cm it is the radius of the Helmholtz coils. V=183.6 I= 1.44 r= 4 e/m= 1.822 x 1011 The actual number would be 1.766 x 1011 Percent of error 1.766 x 10111.822 x 1011 /1.766 x 1011 x 100% Percent of error is 3.17% Analysis The source of error may be due to the imperfection of the apparatus. The machine itself may not be exactly accurate. Also, when measuring the radius, it was a rough estimate as it was difficult to obtain the exact number....
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This note was uploaded on 11/18/2010 for the course ACC 2002 taught by Professor Staff during the Spring '08 term at UChicago.
 Spring '08
 Staff

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