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Recommended: Charge to mass ratio of electron

Introduction
The historical results of this experiment by determination of the charge to mass ratio of an electron allowed physicist to work out the miniscule mass of an electron through the use of an external magnetic field. Magnetic fields apply a magnetic force on charged particles perpendicular to their direction of motion and to the magnetic field itself. This allows for the magnetic force to act as a centripetal force which then, through analysis, allows for the determination of certain charged particles through the analysis of their curve radius. In lab 15, Measurement of Charge to Mass Ratio for Electrons, the objective was to measure the charge to mass ratio (e/m) of an electron through the use of a mercury vapor chamber. This was done through the graphical analysis by the linearized equation (4). The goal was to construct a linear graph in which the slope and slope error was calculated using the Linest function, the slope than allows for the derivation of the charge to mass ratio of an electron. Error propagation (error formulas) was also used in this experiment to account for sources of error that could have occurred.
Equations used:
Kinetic Energy: 1/2mv2=eV, where m is the mass of an electron, v is the electron speed, e is the elementary charge of an electron, and V was the voltage used in the experimental calculation.
Lorentz Force: eVB=m(v2/r) =eV(Bh-Be), this accounts for the centripetal force by making it equal the magnetic force acting on the mercury (electron) beam. Same variables as equation (1) except for r is the radius curvature of the mercury beam, Bh is the Helmholtz coil magnetic field and Be is the Earth’s magnetic field. This equation along with the kinetic energy equation leads to the derivation of...

... middle of paper ...

...hamber to view photons released by de-exciting mercury atoms and the physical phenomenon of the way charged particles are affected in a magnetic field in this lab allowed for the manipulation of current and voltage to produce a value of the charge to mass ratio of an electron. The experimental value was determined to be 3.97x1010 C/Kg, while the theoretical value is 1.76x1011 C/Kg. Thus, this experiment showed accurate results with minor sources of error, determined to be: the affect of the Earth’s magnetic field and imprecise measurements. Ultimately, the physics principles of magnetism, current and voltage were used throughout this experiment. In conclusion, the calculation of the charge to mass ratio of an electron is possible through the use of graphical analysis corresponding to equation (r) and error propagation, creating a successful experimental measurement.

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