Measurement of em

Measurement of em - Measurement of e/m Lab 5 Purpose The...

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Measurement of e/m Lab 5
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Purpose The purpose of this experiment was to experimentally verify the value of e/m. Description An evacuated glass tube in which electrons execute their orbits and a pair of coils to provide a uniform magnetic field within the tube was used in the experiment. The uniform magnetic field that bends the beam is produced by Hemlholtz coils and its strength can be adjusted by varying the current passing through the coils. The electron tube is mounted so that the electron beam emerging from the gun is perpendicular to the field and midway between the coils. Theory The orbit of a charged particle in a uniform magnetic field is a circle when its initial velocity is perpendicular to the field. The radius of the orbit is proportional to the ratio of the charge to mass of the particle. When the strength of the magnetic field and the initial velocity are known, a measurement of the radius of the orbit determines the q/m. This principle was used by J.J. Thomson to measure the charge to mass ratio of the electron in 1897. The particle has a circular orbit because the particle experiences a force that is
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This note was uploaded on 02/16/2010 for the course PHYSICS V85.001100 taught by Professor Lenihan during the Fall '05 term at NYU.

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Measurement of em - Measurement of e/m Lab 5 Purpose The...

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