User:Brian P. Josey/Notebook/Junior Lab/2010/11/08: Difference between revisions
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== | ==e/m Ratio== | ||
This week, my partner, [[User:Kirstin Grace Harriger|Kirstin]], and I did the [[Physics307L:Labs/e over m|e/m ratio]] experiment. This experiment it used to determine the ratio of the charge of an electron to its mass. Combined with the [[Physics307L:Labs/Millikan|Millikan oil drop]] experiment, two fundamental physical quantities can be determined, the mass and the charge of the electron. This quantities are significant in that they are very useful in quantum mechanics, and more importantly, the charge of the electron is the fundamental charge and the smallest amount of charge that can exist on its own. (Some other subatomic particles have fractional charge, but they cannot exist on their own.) | |||
Historically, this experiment was first conducted by [http://en.wikipedia.org/wiki/J._J._Thomson J. J. Thomson] in 1897 using cathode ray tubes. This experiment, however, is a little more updated and has a different approach than the original groundbreaking experiment. In place of the cathode tubes, we have glass tube full of a very dilute helium gas. This tube is surrounded by a Helmholtz coil that can supply a nearly uniform magnetic field throughout the whole tube. In this tube, we will release electrons from a heater plate, focus them into a nearly coherent beam, and apply a varying magnetic field. This varying magnetic field will change the trajectory of the electrons, which emit light from the collisions with the helium, so that it forms a complete circle. We then measured the dimensions of the circular path, and the voltages used to free the electrons to determine the ratio, e/m. | |||
==Set-up== | ==Set-up== | ||
Revision as of 11:19, 14 November 2010
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e/m RatioThis week, my partner, Kirstin, and I did the e/m ratio experiment. This experiment it used to determine the ratio of the charge of an electron to its mass. Combined with the Millikan oil drop experiment, two fundamental physical quantities can be determined, the mass and the charge of the electron. This quantities are significant in that they are very useful in quantum mechanics, and more importantly, the charge of the electron is the fundamental charge and the smallest amount of charge that can exist on its own. (Some other subatomic particles have fractional charge, but they cannot exist on their own.) Historically, this experiment was first conducted by J. J. Thomson in 1897 using cathode ray tubes. This experiment, however, is a little more updated and has a different approach than the original groundbreaking experiment. In place of the cathode tubes, we have glass tube full of a very dilute helium gas. This tube is surrounded by a Helmholtz coil that can supply a nearly uniform magnetic field throughout the whole tube. In this tube, we will release electrons from a heater plate, focus them into a nearly coherent beam, and apply a varying magnetic field. This varying magnetic field will change the trajectory of the electrons, which emit light from the collisions with the helium, so that it forms a complete circle. We then measured the dimensions of the circular path, and the voltages used to free the electrons to determine the ratio, e/m. Set-upEquipment:
Connections:
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