Lab Report
The Charge/Mass (e/m) Ratio of the Electron
PHYS 0212: Introduction to Laboratory Physics Fall 2012
Abstract
The experiment conducted demonstrated correlation between the charge and mass of an electron and the behavior of magnetic fields. The lab was divided into four parts. The first three parts were conducted with a compass that was used to locate the magnetic field lines around a bar magnet, a solenoid and then a pair of Helmholtz coils. As a result of these trials, our observations found evidence that magnetic field lines go from a north magnetic pole to a south magnetic pole. These results were seen in all three magnetic devices. When determining the magnitude of the electric field in the Helmholtz coils, the α value was experimentally determined to be 8.522×10-4 T/A and this value differed by 9.378% from the expected α value of 7.791×10-4 T/A. Lastly, in the fourth part of the experiment, the charge to mass ratio was calculated by bending an electron beam in side an e/m tube with the Helmholtz coils and came out to be 1.158×1011 C/kg, with a 34.17% error from the expected value 1.759×1011 C/kg.
Introduction and Theory
The easiest way to describe magnetic forces is by recognizing that unlike poles attract each other while like poles repel. Kind of like the same way an electrical positive charge is attracted to an electrical negative charge. The main difference between an electrical force and a magnetic force is while positive and negative charges have the ability to be separated, it is not possible to separate opposite poles of a magnet to create what is theoretically known as a magnetic monopole. In fact, if a magnet were cut, it would create two new magnets both with a north and south pole. This phenomenon would be observed in each piece because a north and south pole must always exist opposite each other. Electric and magnetic fields are very similar because both can create electromagnetic waves. Each wave is perpendicular to the other, and are
PHYS 0212: Introduction to Laboratory Physics Fall 2012
Abstract
The experiment conducted demonstrated correlation between the charge and mass of an electron and the behavior of magnetic fields. The lab was divided into four parts. The first three parts were conducted with a compass that was used to locate the magnetic field lines around a bar magnet, a solenoid and then a pair of Helmholtz coils. As a result of these trials, our observations found evidence that magnetic field lines go from a north magnetic pole to a south magnetic pole. These results were seen in all three magnetic devices. When determining the magnitude of the electric field in the Helmholtz coils, the α value was experimentally determined to be 8.522×10-4 T/A and this value differed by 9.378% from the expected α value of 7.791×10-4 T/A. Lastly, in the fourth part of the experiment, the charge to mass ratio was calculated by bending an electron beam in side an e/m tube with the Helmholtz coils and came out to be 1.158×1011 C/kg, with a 34.17% error from the expected value 1.759×1011 C/kg.
Introduction and Theory
The easiest way to describe magnetic forces is by recognizing that unlike poles attract each other while like poles repel. Kind of like the same way an electrical positive charge is attracted to an electrical negative charge. The main difference between an electrical force and a magnetic force is while positive and negative charges have the ability to be separated, it is not possible to separate opposite poles of a magnet to create what is theoretically known as a magnetic monopole. In fact, if a magnet were cut, it would create two new magnets both with a north and south pole. This phenomenon would be observed in each piece because a north and south pole must always exist opposite each other. Electric and magnetic fields are very similar because both can create electromagnetic waves. Each wave is perpendicular to the other, and are
Cited: Clark, Russell J. "The Charge/Mass (e/m) Ratio of the Electron." Introduction to Laboratory Physics. 3rd ed. Dubuque: Kendall Hunt Pub, 2012. 117-30. Print. Cutnell, John D. and Kenneth W. Johnson. Physics. 8th ed. Hoboken: John Wiley & Sons, 2009. Print.