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Register a new userPlancks constant measurement by Landauer quantization for students laboratories
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A simple experimental setup for measuring the Plancks constant, using Landauer quantization of the conductance between touching gold wires, is described. It consists of two gold wires with thickness of 0.5 mm and 1.5 cm length, and an operational amplifier. The setup costs less than $30 and can be realized in every teaching laboratory in two weeks. The usage of oscilloscope is required.
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Motivated by the Dirac idea that fundamental constant are dynamical variables and by conjectures on quantum structure of spacetime at small distances, we consider the possibility that Planck constant $hbar$ is a time depending quantity, undergoing random gaussian fluctuations around its measured constant mean value, with variance $sigma^2$ and a typical correlation timescale $Delta t$. We consider the case of propagation of a free particle and a one--dimensional harmonic oscillator coherent state, and show that the time evolution in both cases is different from the standard behaviour. Finally, we discuss how interferometric experiments or exploiting coherent electromagnetic fields in a cavity may put effective bounds on the value of $tau= sigma^2 Delta t$.
Physics lab courses are an essential part of the physics undergraduate curriculum. Learning goals for these classes often include the ability to interpret measurements and uncertainties. The Physics Measurement Questionnaire (PMQ) is an established open-response survey that probes students understanding of measurement uncertainty along three dimensions: data collection, data analysis, and data comparison. It classifies students reasoning into point-like and set-like paradigms, with the set-like paradigm more aligned with expert reasoning. In the context of a course transformation effort at the University of Colorado Boulder, we examine over 500 student responses to the PMQ both before and after instruction in the pre-transformed course. We describe changes in students overall reasoning, measured by aggregating four probes of the PMQ. In particular, we observe large shifts towards set-like reasoning by the end of the course.
Physics lab courses are integral parts of an undergraduate physics education, and offer a variety of opportunities for learning. Many of these opportunities center around a common learning goal in introductory physics lab courses: measurement uncertainty. Accordingly, when the stand-alone introductory lab course at the University of Colorado Boulder (CU) was recently transformed, measurement uncertainty was the focus of a learning goal of that transformation. The Physics Measurement Questionnaire (PMQ), a research-based assessment of student understanding around statistical measurement uncertainty, was used to measure the effectiveness of that transformation. Here, we analyze student responses to the PMQ at the beginning and end of the CU course. We also compare such responses from two semesters: one before and one after the transformation. We present evidence that students in both semesters shifted their reasoning in ways aligned with the measurement uncertainty learning goal. Furthermore, we show that more students in the transformed semester shifted in ways aligned with the learning goal, and that those students tended to communicate their reasoning with greater sophistication than students in the original course. These findings provide evidence that even a traditional lab course can support valuable learning, and that transforming such a course to align with well-defined learning goals can result in even more effective learning experiences.
In this paper we put forth a model for physics course reform that uniquely uses proven, research-based active learning strategies to help students improve their physics knowledge and problem-solving skills. In this study, we compared the exam performance of students in two sections of the same introductory physics course. One section (the traditional section, N = 258) was taught by an instructor who is highly regarded for his lectures, but did not use any active learning teaching strategies. The other section (the reformed section, N = 217) was taught by an instructor who had never before taught a physics class but who was trained in physics and astronomy education research and who did use active learning teaching strategies. Students in the reformed section significantly outperformed students in the traditional section on common exam questions over the course of the semester, regardless of whether the question was conceptual or quantitative. This reform effort has been successful at improving students learning and significantly increasing the departments use of active learning strategies at the introductory level and beyond.
We describe a study of period changes in 59 RR Lyrae stars, using times of maximum brightness from the GEOS database. The work was carried out by outstanding senior high school students in the University of Toronto Mentorship Program. This paper is written in such a way that high school or undergraduate physics and astronomy students could use it as a guide and template for carrying out original research, by studying period changes in these and other types of variable stars.
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