Vol. 63 No. 2 Jul-Dec (2017): Revista Mexicana de Física E
Published:
2017-01-01
Artículos
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A novel approach to the Child-Langmuir law
Abstract:We analyze the motion of charged particles in a vacuum tube diode using a new set of variables. We obtain the space charge limited current for a charged particle moving non-relativistically in one dimension for the case of zero and non zero initial velocity without solving a nonlinear differential equation. We introduce what we call the microscopic Child-Langmuir law which is valid for the classical and relativistic cases that allows to determine the space charge limited current without solving a nonlinear differential equation.⬇️ Scroll down to see the full summary -
La ciencia en la cultura novohispana: el debate sobre la aurora boreal de 1789
Abstract:On November 14th, 1789 a strange red light was observed over the horizon, toward the north of Mexico City. This phenomenon sparked a debate about the origin and nature of auroras, which were practically unknown in those latitudes. The main participants in the discussion were the editor José Antonio Alzate y Ramírez, the tax collector Antonio León y Gama, and the watchmaker José Francisco Dimas Rangel. Other men of letters also participated as authors of letters and readers. The debate lasted nearly two years, and during that time these savants published nine texts in periodical magazines such as Gazeta de literatura de México, Gazeta de México, as well as in pamphlets. The study of this exchange shows the role of debates in mobilizing different ways of thinking and knowing about nature, as well as in stimulating an incipient public sphere. It also complements our knowledge about science in the culture of the New Spain during the Enlightenment.⬇️ Scroll down to see the full summary -
Materials characterization by analysis of force-distance curves: an introduction to nano-mechanical measures and experimentation for undergraduate students
Abstract:We present an analysis and interpretation of force-distance curves by contact mode AFM in order to obtain the elastic modulus of different materials. For quantitative data analysis, the spring constant of the cantilever was calculated using the thermal tune method achieving consistent results. Although various assumptions were made, the computed Young's Modulus of the samples converges with the ones found in literature. This paper is part of a series of experimental practices that serves as an introduction to the principles of nanotechnology and scientific research for third-year physics undergraduate students. During the development of this work, students are expected to reflect their knowledge and writing skills in the fields of literature review, Hertz's contact mechanics, and computational statistics, and data analysis.⬇️ Scroll down to see the full summary -
Theoretical and experimental study of the normal modes in a coupled two-dimensional system
Abstract:In this work, the normal modes of a two-dimensional oscillating system have been studied from a theoretical and experimental point of view. The normal frequencies predicted by the Hessian matrix for a coupled two-dimensional particle system are compared to those obtained for a real system consisting of two oscillating smartphones coupled one to the other by springs. Experiments are performed on an air table in order to {largely reduce the friction forces}. The oscillation data are captured by the acceleration sensor of the smartphones and exported to file for further analysis. The experimental frequencies compare reasonably well with the theoretical predictions, specifically, within 1.7% of discrepancy.⬇️ Scroll down to see the full summary -
La filosofía frente al objeto cuántico
Abstract:Often, the quantum physics and the story of its development are presented as one of the greatest scientific and intellectual achievements of XX Century. However, and this is not completely new, it is well known that identifying physics as ``revolutionary'' has depended largely on its scientific, theoretical and experimental consequences, but also on the level of the philosophical problems it has vented since its inception. However, from the point of view of philosophy, we consider that, although the current knowledge of the philosophically fertile horizons of quantum physics is not completely limited, it is necessary, in favor of further deepening, to turn our attention to the ontological problem of the quantum object. In this sense this work represents the effort to elaborate a philosophical reflection on the question about the nature of the quantum object. Starting from a general supposition according to which reality is made up of objects, things or entities and that these ``objects'' are found in any physical or philosophical theory, the duty of defining and limiting the ontological status of the entities it postulate is under discussion. However, quantum physics entails a extraordinary difficulty facing this requirement since the behavior and properties of the subatomic entities implies the cancelation of the fundamental ontological principle of identity-causality; its description introduces in the physical world elements such as uncertainty, absence of identity and the lack of punctual locality and, which, in general terms, imply, on one hand the emergency of a new kind of science and on the other hand an ontological reformulation. Given than the objects of quantum theory are far from the ones exhibited by the classic physics, the need to answer the following questions arises: How are, ontologically speaking, the objects postulated by a theory with the peculiarity of quantum physics?, what are they?, how are they and what ontological determinations do those posses?, what ontology is behind these entities? What kind of ontology implies the quantum theory? With all of this under consideration, it is discussed that the ontological focus of quantum physics in terms of potentiality-actuality it is reminiscent to the concepts of ``act'' and ``power'', used in Aristotle Metaphysics in order to explain the transformation of the Being. Finally it is pointed out that the ontology behind quantum mechanics openly shows that reality is far from being even, simple and concrete; it implies a great and growing complexity that appertain to the very self development of the science in general. This philosophical and ontological exam of the quantum entities lead to assert that contemporary science has acquired a multi-paradigmatic character, revealing that reality is not univocal and has different manifestations and ways to be.⬇️ Scroll down to see the full summary
