Assunta Bonanno

Revisiting work–energy theorem's implications

The Galilean invariance of work–energy theorem, at an elementary mechanics level, has not been deeply discussed in the past, nor have its implications in connection with other fundamental mechanical laws been investigated. In this paper we give some further insight into the work–energy theorem, showing that its Galilean invariance implies the impulse theorem. We also introduce a formalism to determine temporal details of motion only by means of energetic considerations. Applications of the formalism are also presented, which are interesting both for graduates and for university undergraduates.

Magnetic interactions and the method of images: a wealth of educational suggestions

Under some conditions, the method of images (well known in electrostatics) may be implemented in magnetostatic problems too, giving an excellent example of the usefulness of formal analogies in the description of physical systems. In this paper, we develop a quantitative model for the magnetic interactions underlying the so-called Geomag™ paradox and describe a quantitative experimental investigation to validate the model. The validity ranges of some approximations involved in this problem are quantitatively discussed and the advantages of a dimensionless formulation of the interaction are pointed out. This work offers many educational suggestions suitable for university students.

Low-cost carbon-based counter electrodes for dye sensitized solar cells

In this work, we present the realization of four carbon-based counter electrodes for dye-sensitized solar cells. The photovoltaic behaviours of counter electrodes realized with graphene, multiwalled carbon nanotubes, and nanocomposites of multiwalled carbon nanotubes and metal nanoparticles are compared with those of classical electrodes (amorphous carbon and platinum). Our results show an increase of about 50% in PCE for graphene and Ag/carbon nanotube electrodes with respect to amorphous carbon and of 25% in comparison to platinum. An improvement in cell stability is also observed; in fact, the PCE of all carbon-based cells assumes a constant value during a period of one month while that with the Pt electrode decreases by 50% in one week.

Reference frame symmetries and conservation laws: Galilean versus Lorentzian

The relation between the symmetry properties of a physical system and conservation laws, although a fundamental topic, is barely treated in educational contexts. In this paper, by only using elementary formalism, we explore the connection between energy–momentum conservation laws with the reference frame invariance either in the Galilean or in the Lorentzian context, which is a fundamental symmetry property of any physical system. Some reflections (pedagogically sound and significant either for graduate and university undergraduate students) are also proposed on the different roles played by space and time in pre-relativistic and relativistic mechanics.

Virtually Exploring A Pillar Of Experimental Physics: The Hertz Experiment

In the present work we report on the implementation and early assessment of a multimedia learning object, developed using the Java programming language, which also integrates in a creative way some internet freely available educational resources, intended to support the teaching/learning process of the historical Hertz experiment.

A ‘sparkling’ low-cost revisitation of the historical Hertz’s experiment

Electromagnetic phenomena involve abstract concepts and models that are particularly problematic for students, especially in the field of electromagnetic (EM) waves. In particular, for these abstract topics it is difficult to plan real experiments that offer the possibility to introduce the basic related concepts. A valid support might come from the revisitation of historical experiments, whose value have been demonstrated from an educational point of view. In this frontline we have planned an educational real-time experiment, which allows students to get in touch with the basic phenomenology of EM waves. It is a modern revisitation of the historical Hertzs experiment that offers the possibility (from a qualitative point of view) to reproduce the Hertzs ideas using low cost and easy to find materials, showing an easy way to generate and to detect an electromagnetic wave. Moreover, the same kind of low cost setup allows performing quantitative measures if coupled with a digital acquisition module, offering the possibility to characterise the main conceptual aspects of an electromagnetic wave, such as the signals dependence on the distance between transmitter and receiver or as the concept (otherwise abstract) of polarisation.

Science-Technology Cross-Hybridization and its Role in the Crisis of the Scientific Method: An Historical Perspective

Nowadays, in the science-related community, an urgent need has emerged to clarify a crisis of the methodological paradigm known as “Scientific Method”. Such a crisis, arising from some recent striking experimental results achieved in experimental sciences, undermines the very foundations of knowledge, with potential serious consequences to the development of future technological applications. In this work, the crisis is analysed within an historical survey on the evolution of the Scientific Method. Furthermore, the role played by cross-hybridization between sciences and technological development is highlighted, throughout the last three centuries, as a possible factor in overcoming that crisis.

Capacitors, Tanks, Springs and the Like: A Multimedia Tutorial

In this work we present an interactive multimedia tutorial allowing to comparatively explore the dynamical behavior of the “Two-capacitor system” and of others systems, quite different, but showing a very similar energetic behavior: (i) two communicating tanks; (ii) two coupled lossy springs “sharing elongation”; (iii) plastic collision between two material points; (iv) two coaxial, rotationally coupled, disks spinning around an axis. The aim of the work is to give learners useful insights on the fundamental subject of energy transformation. The tutorial, appropriate for high school and first year university students, is implemented in a form that makes it also suitable for classroom use with an Interactive White Board.

Archimedes and Caustics: A Twofold Multimedia and Experimental Approach

In this work we present a twofold educational approach to the reflective properties of surfaces, starting from the historical context of Archimedes “burning mirrors”. The properties of the emerging surface known as “caustic” of a given smoothly shaped mirror are illustrated by an interactive multimedia. An experimental device is also proposed to visualize the geometrical principles underlying the formation of caustics. The proposed didactical trail is intended also to contextualize the figure and work of Archimedes in a perspective tightly linked to modern technology, so to collect young learners’ interest.