Physics

A novel method is proposed to measure the refractive indices (RIs) of the materials of different transparent solid state media. To exploit the advantage of non-contact measurement laser beam interferometry is used as an effective technique for this purpose. The RIs of materials are also experimentally determined with the aid of another laser based simple method. The derivations of the working formulae for both the methods are presented. The experimental values of RI of any glass sample found by the different methods are consistent with each other and fall within the range of known values of RI for glass. Both types of experiments can be set up rather easily in an undergraduate laboratory. They can supplement other methods of finding refractive index like, for example, methods based on the use of a spectrometer.

Without any major changes, a pilot version of a physical science lab course was able to continue when the COVID-19 crisis necessitated the abrupt suspension of on-campus education. The 'Maker Lab' course, in which students conceive and set up their own experiments using affordable microcontrollers, required students to follow the entire arc of an empirical research cycle twice. The decision for and facilitation of such open-inquiry projects was based on and warranted by the literature on teaching the process of experimental research and methods of scientific research. The flipped classroom approach was used, where contact time is devoted to discussions and the students' actual experiments were carried out independently at home or elsewhere without the in-person supervision of an instructor. Despite the COVID-19 measures, all students were able to produce interesting and successful research projects. While there were of course difficulties encountered due to the abrupt transition to online teaching, we found several counterbalancing advantages that bear consideration for inclusion even when all teaching activities can return to campus. We believe that three components in the design of the course were vital to the resilience of the course: the choice for fully open-inquiry projects, the decision to use Arduinos as measurement tools, and the flipped aspect of the instruction methods. We also include considerations for adapting these pandemic-resilient methods in other courses and programs.

When a coin is placed on the neck of a cold bottle, the coin will move cyclically. This is caused by the expansion of the gas inside the bottle warming up, which will cause the coin to rise when the internal pressure is large enough to overcome the weight of the coin. This problem, widely used to qualitatively demonstrate several laws of thermodynamics, has no quantitative solution in the literature. For this we use the ideal gas model and Newton's law of cooling combined with computational numerical simulations and systematic experimental measures to confront our theoretical model, including equations for the evolution of temperature, pressure and behaviour of the coins in the system.

Active methodologies aim to develop a critical sense of what is learned, relating theoretical concepts to the practical environment. In this work, we propose an active teaching-learning methodology for laboratory classes in which the student has the autonomy to propose scripts and equipment, instead of following a practice roadmap already defined (built by the teacher or made available by manufacturers for their science kits), in accordance with the theoretical knowledge acquired. The objective is to encourage the student to be the protagonist in experimental activities, based on the theoretical knowledge acquired in the classroom. In this way, we split the method into three parts, namely: (i) Theoretical exposition, (ii) theoretical seminar and proposition of the experimental script and (iii) seminar for the exposition of the experiment carried out. Each of these steps is guided by one or more professional skills, such as: innovation, creativity, proactivity, protagonism, critical sense and scientific thinking, aiming to bring the academic environment to the professional environment.

In a paper ( posthumously ) co-authored by Isaac Newton himself, the primacy of geometric notions in pedagogical expositions of centripetal acceleration has been clearly asserted. In the present paper we demonstrate how this pedagogical prerogative can inform the design of an experiment involving an accelerometer-equipped smartphone rotating uniformly in a horizontal plane. Specifically, the location of the sensor itself within the body of the smartphone will be determined using a technique that is purely geometrical in nature, relying on nothing more than the notion that centripetal accelerations are centrally-pointing. The complete absence of algebraic manipulations obliges students to focus exclusively on the development of their geometrical reasoning abilities. In particular, it provides a healthy challenge for those algebraically-accomplished students for whom equations, calculations and data tables represent a means of avoiding a direct confrontation with the imposing spectre of material that is otherwise purely conceptual in nature.

We describe a simple classroom demonstration of a fluid-dynamic instability. The demonstration requires only a bucket of water, a piece of string and some used tealeaves or coffee grounds. We argue that the mechanism for the instability, at least in its later stages, is two-dimensional barotropic (shear-flow) instability and we present evidence in support of this. We show results of an equivalent basic two-dimensional numerical non-linear model, which simulates behavior comparable to that observed in the bucket demonstration. Modified simulations show that the instability does not depend on the curvature of the domain, but rather on the velocity profile.

The main aim of this article is that students, at the basic level of education, gain a quantitative understanding of the size of molecules by performing a simple experiment easily designed within the classroom.

In this paper, we designed and experimentally studied several systems of standard coaxial cables with different impedances which mimic the operation of so called photonic structures like coupled photonic crystal microcavities. Using elementary cells of half-meter long coaxial cables we got resonances around 100MHz, a range of frequencies that can be easily studied with a standard teaching laboratory apparatus. Resonant mode frequency splitting has been obtained in the case of double and triple coupled cavities. A good agreement between experimental results and transfer matrix model has been observed. The aim here is to demonstrate that standard coaxial cable system is a very cheap way and an easy to implement structure to explain to undergraduate students complex phenomena that usually occur in the optical domain.

Science students must deal with the errors inherent to all physical measurements and be conscious of the necessity to express their as a best estimate and a range of uncertainty. Errors are routinely classified as statistical or systematic. Although statistical errors are usually dealt with in the first years of science studies, the typical approaches are based on performing manually repetitive observations. Here, based on data recorded with the sensors present in many mobile devices a set of laboratory experiments to teach error and uncertainties is proposed. The main aspects addressed are the physical meaning of the mean value and standard deviation, and the interpretation of histograms and distributions. Other activities focus on the intensity of the fluctuations in different situations, such as placing the device on a table or held in the hand in different ways and the number of measurements in an interval centered on the mean value as a function of the width expressed in terms of the standard deviation. As applications to every day situations we discuss the smoothness of a road or the different positions to take photographs both of them quantified in terms of the fluctuations registered by the accelerometer. This kind of experiments contributes to gaining a deep insight into modern technologies and statistical errors and, finally, to motivate and encourage engineering and science students.

In this work, we present the results of a research in which we aimed to evidence obstacles and advances in pre-service teachers' conceptualization on a subject involving elementary Quantum Mechanics. We based our analysis on the theories due to David Ausubel and Gèrard Vergnaud to study Meaningful Learning patterns, both in predicative and operator form of knowledge, of six students involved in a didactical intervention composed of six classes, in which we emphasized both similarities and differences between Classical and Quantum Physics. With this intervention, we intended to teach the concepts of Physical Systems, Dynamical Variables, State of a Physical System and Time Evolution. We guided our data analysis by the methodology of content analysis and it turned possible to map Meaningful Learning patterns involving the four concepts to which were associated a set of essential features in the predicative stage and a set of theorems-in-action in the operatory stage relating the aim-concepts in problem-solbing or conceptual mapping.