Short circuit, electrical overloads, power line losses and electrical injury, but also circuit breaker and fuse, leakage current protector, power transformation and protection against electric shock. All these terms are connected with the mystery of operation in eletric power distribution systems. Let us join electricity on its journey from power station to everyone's socket. What do we experience on this adventurous journey? Sometimes there may be even a risk of death! Fortunately, thanks to the sophisticated application of physical principles of electricity and magnetism, most of the threats are avoided. Will we be able to uncover the veil of physical electricity site or will it defend its secrets?

An artificially structured boundary (ASB) produces a short-range, static electromagnetic field that can reflect charged particles. In the work presented, an ASB is considered to consist of a spatially periodic arrangement of electrostatically plugged magnetic cusps. When used to create an enclosed volume, an ASB may confine a non-neutral plasma that is effectively free of applied electromagnetic fields, provided the spatial period of the ASB-applied field is much smaller than any one dimension of the confinement volume. As envisioned, a non-neutral positron plasma could be confined by an ASB along its edge, and the space-charge of the positron plasma would serve to confine an antiproton plasma. If the conditions of the two-species plasma are suitable, production of antihydrogen via three-body recombination for antimatter gravity studies may be possible. A classical trajectory Monte Carlo (CTMC) simulation suite has been developed in C++ to efficiently simulate charged particle interactions with user defined electromagnetic fields. The code has been used to explore several ASB configurations, and a concept for a cylindrically symmetric ASB trap that employs a picket-fence magnetic field has been developed. Particle-in-cell (PIC) modeling has been utilized to investigate the confinement of non-neutral and partially neutralized positron plasmas in the trap.

In this study, a computational approach to the solution of an inverse modeling problem is developed to reconstruct unknown material properties of a Li-ion battery. In-situ MRI measurements performed on a layered graphite electrode during charging are used in comparison with Stefan-Maxwell concentrated electrolyte theory, Butler-Volmer reaction kinetics, and multiphase porous electrode theory to explore the overall accuracy of models for Li transport processes in the active material. In particular, the main research goal here is to determine if the original Cahn-Hilliard formulation for phase-separation can be improved upon through extension to a periodic bilayer model (two-layer Cahn-Hilliard). The original model contains a pair of two stable phases at low and high concentrations that produces the ``shrinking core'' behavior for lithiated graphite. The comparative advantage of the periodic bilayer model stems from the capturing of a third stable phase of intermediate concentration as the average between one concentrated layer and one dilute layer. Calibration is done simultaneously on concentration and cell voltage profiles through multi-objective optimization where the accuracy of a model is assessed based on the quantification of agreement with experimental data. The periodic bilayer model is found to improve upon the least-squares error for fitting of concentration profiles by roughly 20%, while the voltage fittings are too similar to be conclusive. / Thesis / Master of Science (MSc)

Various anomalous effects that emerge when the interfaces between media are involved in sound-matter or light-matter interactions are studied. The three specific systems examined are a fluid channel between elastic metal plates, a linear chain of metallic perforated cylindrical shells in air, and a metal-dielectric slab with the interfaces treated as finite regions of smoothly changing material properties. The scattering of acoustic signals on the first two is predicted to be accompanied by the effects of redirection and splitting of sound. In the third system, which supports the propagation of surface plasmons, it is discovered that the transition region introduces a nonradiative decay mechanism which adds to the plasmon dissipation. The analytical results are supported with numerical simulations. The outlined phenomena provide the ideas and implications for applications involving manipulation of sound or excitation of surface plasmons.

Recently, based on the physics of viscosity, we developed a new technology, which utilizes electric or magnetic fields to change the rheology of complex fluids to reduce the viscosity, while keeping the temperature unchanged. The method is universal and applicable to all complex fluids with suspended particles of nano-meter, sub-micrometer, or micrometer size. Completely different from the traditional viscosity reduction method, raising the temperature, this technology is energy-efficient, as it only requires small amount of energy to aggregate the suspended particles. In this thesis, we will first discuss this new technology in detail, both in theory and practice. Then, we will report applications of our technology to energy science research. Presently, 80% of all energy sources are liquid fuels. The viscosity of liquid fuels plays an important role in energy production and energy conservation. With an electric field, we can reduce the viscosity of asphalt-based crude oil. This is important and useful for heavy crude oil and off-shore crude oil production and transportation. Especially, since there is no practical way to raise the temperature of crude oil inside the deepwater pipelines, our technology may play a key role in future off-shore crude oil production. Electrorehology can also be used to reduce the viscosity of refinery fuels, such as diesel fuel and gasoline. When we apply this technology to fuel injection, the fuel droplets in the fuel atomization become smaller, leading to faster combustion in the engine chambers. As the fuel efficiency of internal combustion engines depends on the combustion speed and timing, the fast combustion produces much higher fuel efficiency. Therefore, adding our technology on existing engines improves the engine efficiency significantly. A theoretical model for the engine combustion, which explains how fast combustion improves the engine efficiency, is also presented in the thesis. / Physics

In this study, we tested the performance of ChatGPT-4 on the concept inventory Brief Electricity and Magnetism Assessment (BEMA) to understand its potential as an educational tool in physics, especially in tasks requiring visual interpretation. Our results indicate that ChatGPT-4 performs similarly to undergraduate students in introductory electromagnetism courses, with an average score close to that of the students. However, ChatGPT-4 displayed significant differences compared to students, particularly in tasks involving complex visual elements such as electrical circuits and magnetic field diagrams. While ChatGPT-4 was proficient in proposing correct physical reasoning, it struggled with accurately interpreting visual information. These findings suggest that while ChatGPT-4 can be a useful supplementary tool for students, it should not be relied upon as a primary tutor for subjects heavily dependent on visual interpretation. Instead, it could be more effective as a peer, where its outputs are critically evaluated by students. Further research should focus on improving ChatGPT’s visual processing capabilities and exploring its role in diverse educational contexts.

The objective of this study is to examine core-shell type plasmonic metamaterials aimed at the development of materials with unique electromagnetic properties. The building blocks of metamaterials under study consist of gold as a metal component, and silica and precipitated calcium carbonate (PCC) as the dielectric media. The results of this study demonstrate important applications of the core-shells including scattering suppression, airborne obscurants made of fractal gold shells, photomodification of the fractal structure providing windows of transparency, and plasmonics core-shell with a gain shell as an active device. Plasmonic resonances of the metallic shells depend on their nanostructure and geometry of the core, which can be optimized for the broadband extinction. Significant extinction from the visible to mid-infrared makes fractal shells very attractive as bandpass filters and aerosolized obscurants. In contrast to the planar fractal films, where the absorption and reflection equally contribute to the extinction, the shells' extinction is caused mainly by the absorption. This work shows that the Mie scattering resonance of a silica core with 780 nm diameter at 560 nm is suppressed by 75% and only partially substituted by the absorption in the shell so that the total transmission is noticeably increased. Effective medium theory supports our experiments and indicates that light goes mostly through the epsilon-near-zero shell with approximately wavelength independent absorption rate. Broadband extinction in fractal shells allows as well for a laser photoburning of holes in the extinction spectra and consequently windows of transparency in a controlled manner. Au fractal nanostructures grown on PCC flakes provide the highest mass normalized extinction, up to 3 m^2/g, which has been demonstrated in the broad spectral range. In the nanoplasmonic field active devices consist of a Au nanoparticle that acts as a cavity and the dye molecules attached to it via thin silica shell as the active medium. Such kind of devices is considered as a nano-laser or nano-amplifier. The fabricated nanolasers were studied for their photoluminescence kinetic properties. It is shown that the cooperative effects due to the coupling of dye molecules via Au nanoparticle plasmons result in bi-exponential emission decay characteristics in accord with theory predictions. These bi-exponential decays involve a fast superradiant decay, which is followed by a slow subradiant decay. To summarize, this work shows new attractive properties of core-shell nanoparticles. Fractal Au shells on silica cores prove to be a good scattering suppressor and a band pass filter in a broadband spectral range. They can also be used as an obscurant when PCC is used as the core material. Finally, gold nanoparticles coated with silica with dye results in bi-exponential decays.

Various nanostructured materials display unique and interesting optical properties. Specific nanoscale objects discussed in an experimental perspective in this dissertation include optical metamaterials, surface plasmon sensors, and two-dimensional materials. These nanoscale objects were fabricated, investigated optically, and their applications are assessed. First, one-dimensional magnetic gratings were studied, followed by their two-dimensional analog, the so-called "fishnet." Both were fabricated, characterized, and their properties, such as waveguiding modes, are examined. Interestingly, these devices can exhibit optical magnetism and even negative refraction; however, their general characterization at oblique incidence is challenging due to diffraction. Here, a new method of optical characterization of metamaterials which takes into account diffraction is presented. Next, surface plasmon resonance (SPR) was experimentally used in two schemes, for the first time, to determine the transition layer characteristics between a metal and dielectric. The physics of interfaces, namely the singularity of electric permittivity and how it can be electrically shifted, becomes clearer owing to the extreme sensitivity of SPR detection mechanisms. Finally, ultra-thin two-dimensional semiconducting materials had their radiative lifetime analyzed. Their lifetimes are tuned both by number of atomic layers and applied voltage biasing across the surface, and the changes in lifetime are suspected to be due to quenching or enhancement of non-radiative process rates.

The purpose of this study was to investigate physics undergraduate students’ conceptual change in the concepts of electric potential and energy (EPE) and electromagnetic induction (EMI). Along with this, categorization of students’ conceptions was done based on students’ epistemological and ontological descriptions of these concepts. In addition, the effect of cognitive perturbation using physics interactive simulations (CPS) in relation to cognitive conflict using physics interactive simulations (CCS) was investigated. A pragmatic mixed methods approach was used in a quasi-experimental design. Data were collected by using the modified Diagnostic Exam of Electricity and Magnetism (DEEM), focus group discussions (FGD) and concept maps (CM). Framework analysis was conducted separately on FGD and CM qualitative data to categorize students’ conceptions while concentration analysis was used to categorize students’ responses to the modified DEEM into three levels, during pre and post intervention. In the qualitative results, six categories of alternative conceptions (naive physics, lateral alternative conceptions, ontological alternative conceptions, Ohm’s P-Primes/ P-Primes, mixed conceptions and loose ideas) and two categories of conceptual knowledge (hierarchical and relational) were identified. The alternative conceptions were less frequently and inconsistently revealed within and across the categories. It was concluded that the categories have common characteristics of diversified distribution of alternative conceptions and multiple alternative conceptions of specific concepts within and across the categories. Most of the categories found in pre intervention persisted in post intervention, but with a lesser percentage extensiveness of categories of alternative conceptions in the CPS than in the CCS class and more percentage extensiveness of categories of conceptual knowledge in the CPS than in the CCS class. ANCOVA was separately conducted on the scores of 45 students on the modified DEEM and CM tests to compare the effectiveness of the CCS and CPS. The results showed a significant difference between the two classes of the post test scores on the DEEM test, (1, 36) = 4.66, p=0.04 and similarly, on the CM test, (1, 31) = 8.33, p=0.007. Consequently, it was concluded that there is a statistically significant difference between CPS and CCS in changing students’ alternative conceptions towards scientific conceptions favoring CPS. To characterize and compare students’ conceptual change of both treatment classes, Hake’s average normalized gain <g> from pre to post scores (the modified DEEM and the CM) were analyzed. Finally, it is suggested that in abstract conceptual areas of EM, cognitive perturbation through interactive simulations is more effective than cognitive conflict through interactive simulations in facilitating conceptual change, and, thus, should guide classroom instruction in the area. Furthermore, recommendations are also suggested for guiding future research in this area. / Science and Technology Education / D. Phil. (Mathematics, Science and Technology Education (Physics Education))

The purpose of this study was to investigate physics undergraduate students’ conceptual change in the concepts of electric potential and energy (EPE) and electromagnetic induction (EMI). Along with this, categorization of students’ conceptions was done based on students’ epistemological and ontological descriptions of these concepts. In addition, the effect of cognitive perturbation using physics interactive simulations (CPS) in relation to cognitive conflict using physics interactive simulations (CCS) was investigated. A pragmatic mixed methods approach was used in a quasi-experimental design. Data were collected by using the modified Diagnostic Exam of Electricity and Magnetism (DEEM), focus group discussions (FGD) and concept maps (CM). Framework analysis was conducted separately on FGD and CM qualitative data to categorize students’ conceptions while concentration analysis was used to categorize students’ responses to the modified DEEM into three levels, during pre and post intervention. In the qualitative results, six categories of alternative conceptions (naive physics, lateral alternative conceptions, ontological alternative conceptions, Ohm’s P-Primes/ P-Primes, mixed conceptions and loose ideas) and two categories of conceptual knowledge (hierarchical and relational) were identified. The alternative conceptions were less frequently and inconsistently revealed within and across the categories. It was concluded that the categories have common characteristics of diversified distribution of alternative conceptions and multiple alternative conceptions of specific concepts within and across the categories. Most of the categories found in pre intervention persisted in post intervention, but with a lesser percentage extensiveness of categories of alternative conceptions in the CPS than in the CCS class and more percentage extensiveness of categories of conceptual knowledge in the CPS than in the CCS class. ANCOVA was separately conducted on the scores of 45 students on the modified DEEM and CM tests to compare the effectiveness of the CCS and CPS. The results showed a significant difference between the two classes of the post test scores on the DEEM test, (1, 36) = 4.66, p=0.04 and similarly, on the CM test, (1, 31) = 8.33, p=0.007. Consequently, it was concluded that there is a statistically significant difference between CPS and CCS in changing students’ alternative conceptions towards scientific conceptions favoring CPS. To characterize and compare students’ conceptual change of both treatment classes, Hake’s average normalized gain <g> from pre to post scores (the modified DEEM and the CM) were analyzed. Finally, it is suggested that in abstract conceptual areas of EM, cognitive perturbation through interactive simulations is more effective than cognitive conflict through interactive simulations in facilitating conceptual change, and, thus, should guide classroom instruction in the area. Furthermore, recommendations are also suggested for guiding future research in this area. / Science and Technology Education / D. Phil. (Mathematics, Science and Technology Education (Physics Education))