Examinando por Autor "Hernandez, Eder"

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    Analysis and comparison of students' conceptual understanding of symmetry arguments in Gauss's and Ampere's laws
    (American Physical Society, 2023-01) Campos, Esmeralda; Hernandez, Eder; Barniol, Pablo; Zavala, Genaro
    Identifying students' difficulties in understanding Gauss's and Ampere's laws is important for developing educational strategies that promote an expertlike understanding of the field concept and Maxwell's equations of electromagnetic phenomena. This study aims to analyze and compare students' understanding of symmetry when applying Gauss's and Ampere's laws to calculate the electric or magnetic field. We conducted a study to analyze how students reason regarding the symmetry conditions necessary to apply Gauss's or Ampere's laws to calculate the electric or magnetic field in three inverse problems. We applied two open-ended questionnaires with parallel surface features, one for Gauss's law and the other for Ampere's law, to 322 engineering students. The three inverse problems present different scenarios with the common characteristic that there is no sufficient symmetry to solve the electric or magnetic field from its corresponding equation. We analyzed students' answers with a phenomenographic approach, focusing on students' answers to a yes or no question and their reasoning. The main findings of the study are the descriptive categories of understanding and the comparison of the categories between contexts (outcome space). The correct reasoning is identifying the necessary symmetry to apply Gauss's or Ampere's law. The other categories refer to the surface features of each scenario to explain students' answers, applying Gauss's or Ampere's law in an oversimplified way and thinking that it would be possible but more complicated in these scenarios. The descriptive categories are related to some of the difficulties previously reported in the literature with standard problems involving Gauss's and Ampere's laws. However, inverse problems elicited variations in the types of reasoning related to the surface features of the scenarios and their parallel representations. The comparative analysis between the electricity and magnetism contexts allowed for identifying that analyzing currents can be more challenging for students than analyzing point charges. This study's findings can guide introductory and intermediate electricity and magnetism instructors to redirect their approach to Gauss's and Ampere's laws by introducing the analysis of inverse problems. © 2023 authors. Published by the American Physical Society.
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    Phenomenographic analysis and comparison of students' conceptual understanding of electric and magnetic fields and the principle of superposition
    (American Physical Society, 2021-12) Campos, Esmeralda; Hernandez, Eder; Barniol, Pablo; Zavala, Genaro
    There are studies of students' understanding of the concept of the electric field, the magnetic field, and the use of the superposition principle that have contributed to the creation of both educational strategies and assessment tools. However, the difficulties of these two concepts have not been compared comprehensively. Therefore, this study aims to compare students' conceptual understanding of electric and magnetic fields in questions regarding the field created by one source and the field produced by a system of two sources. We focus our study on students' explanations about the magnitude and direction of the field and their application of the superposition principle in both contexts (electric and magnetic). We conducted this study with 322 engineering students in a Mexican university. We designed two versions of an open-ended questionnaire, one with the context of electricity and the other with magnetism. We created the questions using the parallelism between electricity and magnetism and used schematic representations with similar surface features to represent this parallelism. Analyzing the data through a phenomenographic approach, the students' drawings and explanations gave insight into their understanding of the concept of field and the superposition principle application in the context of electricity and magnetism. We found that students have similar categories of understanding the concept of the electric and the magnetic field. In both contexts, there is an evident relationship between applying the principle of superposition and understanding the concept of field. We found that there is a greater tendency that a student correctly applies the superposition principle if that student has a robust representation of the field. We found evidence that students consistently merge two different representations (vector plots and field lines) in electricity and magnetism. We named this category of representation "hybrid vectors and field lines."We also found that some students who draw hybrid representations of the field can still apply the superposition principle correctly. However, some conceptual understanding difficulties are dependent on the context: the known difficulty of confusion between forces and fields is more attached to the electricity context. The confusion between electricity and magnetism concepts is more relevant in the magnetism context. As in other literature, we found more evidence that the correct answer in multiple-choice questions may lead students who have mild difficulties (such as memorization and creating a hybrid representation) to choose a correct answer. We recommend that teachers and researchers of electricity and magnetism acknowledge the relationship between the conceptual understanding of the field and applying the superposition principle. We suggest that instructors be attentive to how they approach using representations of electric and magnetic fields. © 2021 authors. Published by the American Physical Society.
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    Phenomenographic analysis of students' conceptual understanding of electric and magnetic interactions
    (American Physical Society, 2022-07) Hernandez, Eder; Campos, Esmeralda; Barniol, Pablo; Zavala, Genaro
    Studying students' problem-solving abilities in physics education research has consistently shown that novices focus on a problem's surface features rather than its physical principles. Previous research has observed that some electricity and magnetism students confuse electricity and magnetism concepts, often presented in parallel problems (or problems with similar surface features). This confusion has been referred to as interference. It is essential to compare students' performance in these problems to evaluate their understanding of these topics. The present work focuses on the students' understanding of interactions between charged particles (i.e., electric force) and electric currents (i.e., magnetic force). We present and compare the findings on students' conceptions when analyzing electric and magnetic interactions for different systems of field sources. We conducted this study with engineering students finishing a calculus-based course on electricity and magnetism. We administered a written, open-ended questionnaire with two sets of three items: one version contained only electricity problems, and the other contained only magnetism problems. Each item in the electricity version of the test had a parallel counterpart in the magnetism version. We used a phenomenographic approach to analyze our data to identify categories that emerged from students' answers. We identified four main ideas in the results: (a) the rule of signs (ROS), which does not evidence a complete conceptual understanding of electric interactions; (b) the force-field confusion due to the similarity of electricity and magnetism contexts; (c) the importance of semiotic representation when answering an electricity and magnetism problem, where the student's choice of representation indicates their understanding, and (d) the interference phenomenon, in which we find evidence of other factors besides those produced by the timing of instruction and administration of the tests. At the end of this work, we provide recommendations for instruction. © 2022 authors. Published by the American Physical Society.
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    Students' conceptual understanding of electric flux and magnetic circulation
    (American Physical Society, 2023-01) Hernandez, Eder; Campos, Esmeralda; Barniol, Pablo; Zavala, Genaro
    Electricity and magnetism are closely related phenomena with a well-known symmetry found in Maxwell equations. An essential part of any electricity and magnetism course includes the analysis of different field source distributions through Gauss's and Ampere's laws to compute and interpret different physical quantities, such as electric flux, electric and magnetic field, or magnetic circulation. Still, some students have difficulties with these calculations or, in some cases, identifying the differences between those quantities. We present this article to explore and compare the challenges that students experience when asked to compute the electric flux (surface integral of the electric field) or the magnetic circulation (line integral of the magnetic field) in a nonsymmetric field-source distribution with two opposite field sources inside a Gaussian spherical surface or Amperian circular trajectory. The sample consisted of 322 engineering students finishing an electricity and magnetism course. They were presented with two parallel problems. Half answered one in the electricity context and the other in the magnetism context. After a phenomenographic analysis, our results showed that the students' conceptual difficulties in both contexts can be grouped into the same categories but are not contextually parallel, as has happened when analyzing other electricity and magnetism concepts. Our results also suggest that the magnetic circulation concept is far more unfamiliar to students than the electric flux. We propose several factors that could explain this finding and suggest teaching to address the conceptual difficulties identified in our analysis. © 2023 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.