Category Archives: Advanced EM

Advanced Electromagentism (Phys 341)

Project Proposal: Modeling Capacitors

I intend to model the capacitance, energy storage capabilities, and fringing fields of capacitors. The assumption of infinite area will be discarded in favor of using analytic approaches whenever possible; for example, one could start with Coulomb’s Law for a surface charge density:

where  is the separation vector between a source point and the field point. From here, one can theoretically model the electric field of a sheet of arbitrary shape and charge density. I will start with a uniform charge density and a simply shaped sheet and work up to more complicated, realistic arrangements of positive and negative plates (i.e. capacitors, though not necessarily parallel plate capacitors only).

When a capacitor with a vacuum between the plates has been satisfactorily described, the effects of dielectrics placed between the plates could be modeled. Exotic dielectric media could be explored. If feasible, these realistic simulated capacitors could be incorporated into an RLC circuit model. As stated above, analytic solutions will be preferred, with approximations used only when the exact answer is computationally impractical. Approximations can, however, be used often as reality checks, as well as to compare the accuracy and computational requirements of approximations with those of the analytic solution.

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Project Proposal: Modeling Optical Filters

When analyzing the brightness of a star, or a mode of a laser beam we observe the effects of that object. In this case we gather photons, and we use tools to gather as much radiation as possible. This data is then transmitted onto a screen to see a representation of what is actually going on. When an electric signal is sent to an oscilloscope, are we actually seeing the signal? A spectrum of light must enter through a series of optical and electrical things before being displayed, and those things can and do distort the image. These are optical filters. Sometimes this is done intentionally to block out certain frequencies, but other times the distortion is unavoidable. By understanding the convolution of electromagnetic waves one can isolate the desired data from the signal presented. I will model using Mathematica different spectra and examine how convolution and deconvolution work as means of setting up usable data.

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Project Proposal: Electric & Magnetic Field Modeling

For my project, I will work with Peter Florio to model the electric and magnetic fields of a bar magnet, sphere and cylinder. I will be looking at the magnetic fields of these distributions in 3-space and modeling their vector fields using Mathematica and Maxwell’s Equations. Problems given in David Griffiths’ Introduction to Electrodynamics will be used as specific examples of these kinds of charge distributions. My results will then be compared to the electric fields of the same distributions found by Peter.

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Project Proposal – Scattering and the Interstellar Medium (ISM)

For my project, I will be studying Mie scattering and it’s relevance to the study of the interstellar medium. The ISM, the space between stars and galaxies, is filled with gas (atomic and molecular), dust, and is permeated by radiation – starlight. Observations of various astrophysical phenomena show that along a given line of sight, their is “extinction” of this radiation. Scattering and absorption account for these observations and occur due to the presence of various dust grains within the ISM. I will model Mie scattering and look at the asymmetry parameter g, a measure of the fraction of light scattered in the forward direction, in an effort to model the relationship between this value and dust grain properties  such as size, composition, etc.

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Project Proposal: Diffraction Symmetries of C. elegans

The C. elegans nematode is a common subject of biological studies, and has become more and more popular in physics research. I intend to find the diffraction patterns generated by the worms’ shape and log the findings into a Symmetries Library (with the eventual goal of using Group Theory to get the worm shape directly from a diffraction image).

The shape of the worm (photos to be taken with a microscope) will correspond to a particular diffraction pattern. I will model the Fraunhoufer diffraction patterns (Far-Field diffraction) of the electromagnetic waves (light waves) by generating images with Mathematica using the Fourier Transforms. The idea is that $\left | Fourier Transform | \right ^2 $ = the diffraction pattern. This project is a study of the behaviors of light waves.

I will eventually be keeping a log of my findings on the already existing website, the Diffraction Symmetries Library.

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Project Proposal: Modeling of EM Fields for Spheres in Mathematica

For my project, I propose the modeling of electromagnetic fields for spheres. I will use Mathematica to start, and possibly attempt to use other software products as well, such as OriginLab or MatLab. I will begin with the simplest case of a hollow sphere with radius approaching zero, or a point charge. I will then model electric fields for conducting spheres of different radii. From there, I will attempt other cases as well, potentially including: concentric spheres, spherical dielectrics, and systems of multiple spheres. Additionally, I will attempt to model magnetic fields for currents traveling in a spherical conductor, and magnetic fields within and surrounding spherical dielectrics. 

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Project Proposal: Modeling E and B Fields of a Toroidal Conductor to Explore Tokamak Plasmas

I am interested in trying to determine why existing tokamaks (toroidal magnetic fusion reactors) use tori with the aspect ratios that they do.  To determine this, I intend to model the electric and magnetic fields (and D and H) of a solid toroidal conductor with a current flowing through it, and to examine how these fields change when the aspect ratio is varied.  I will chose the material properties of the conductor based on fusion plasmas in operating reactors.  Modeling the plasma as a solid seems reasonable due to the fact that tokamak plasmas do not change shape significantly during operation, and, other than some fluid dynamics disturbances, the plasma is relatively stable.

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E & M 341 spring project: Modeling Railguns with John Loree and Elias Kim

Railguns are some of the most powerful weapons currently in production. However, along with being incredibly powerful, they are ideal for civilian use in aerospace engineering, or transportation. Elias Kim and I plan to build, model, and explore the physics behind these impressive devices, modeling the system with Mathematica. We plan to split the project into two parts, one individual modeling the circuitry of the railgun, and the other modeling the inductance and forces upon the railgun in matter, then combining our work to produce equations of motion. Additionally, we intend to build a small scale railgun, test-fire it, and compare its actual efficiency to the model generated earlier in the project.

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E and M Spring Project

Our project for this course is Modeling electric and magnetic fields of a bar magnet, a cylinder, and a sphere using mathematica. I will be modeling the electric and magnetic fields for a cylinder. After developing a model for a general cylinder, I plan on modeling the electric and magnetic fields for different types of cylindrically shaped matter. This includes conductors and dielectrics. I would also like to do this for items with different current levels and to also model the magnetic field for different magnets (paramagnets, diamagnets, and ferromagnets). With this, I want to create a model for more complex systems, such as solenoids.

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Developing Models of RLC Circuits

For my project, I will study RLC circuits. RLC circuits have three main components; resistors, inductors, and capacitors. These circuits are important because of their prevalence in radios and televison (among other things). Specifically, I will develop a few different configurations of these circuits and measure characteristics such as voltage, current, resonance, and most importantly, damping. The physics that governs RLC circuits relies heavily on the mathematics of differential equations. For this reason, Mathematica, due to its strong capabilities in regards to differential equations, is the ideal program to use to model and study these systems.

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