Physics Students’ Conceptual Understanding of Electricity and Magnetism in Nine Years Basic Education in Rwanda

We investigate students’ misconceptions in electrostatics, direct current (DC) and magnetism which are important in electricity and magnetism. We developed and administered a multiple-choice questionnaire test to reveal students’ misconceptions related to charged bodies, lightning, electric fields, electric potential, forces, DC resistive electric circuits and magnets. This test aimed at obtaining quantitative information about misconceptions and was administered to 380 senior two students from Nine Year Basic Education (9YBE) Schools. The selected students have some experience with the new Rwandan secondary physics Competence Based Curriculum (CBC) that is currently under implementation. We find that senior two students have several common misconceptions related to these concepts. The data indicate that although students have some backgrounds on the subject matter, they still seem to believe that if the two charges are separated by a distance, a large-charged object exerts a greater force of attraction or repulsion on the small one. Considerable number of participated students held the misconception of considering current consumption in the resistor/bulb or the electrical devices in the circuits. They also believed that the battery was a continuous current source. The findings also revealed that students held a misconception that a bar magnet when broken into pieces, it is demagnetized. Moreover, a considerable number of participants hold the misconception that all metals are attracted by a magnet. Our study also revealed some of the statistically significant differences in terms of either gender or location of schools for some items.

The application of multiple parallel diodes to control large currents

This paper discusses a few issues concerning diodes and their application in electric circuits. Considering voltage and current restrictions, experimental and theoretical efforts are made to safely apply semiconducting diodes in circuits working with large current regimes. Combinations of diodes and protecting resistors connected in series and parallel have demonstrated to be of great help with the task of controlling electric currents. To this aim, several activities have enabled participants to observe and measure, or to calculate and display valuable data. Therefore, important class conclusions are stated.

Performance Improvement in Steam Turbine in Thermal Power Plants Using Artificial Neural Network

Artificial intelligence has proven its effectiveness in many industrial fields to enhance the existing functionality. Artificial intelligence and machine learning algorithms integrated with turbines can be useful in controlling important variables such as pressure, temperature, speed, and humidity. In this research, the Simulink library from MATLAB is used to build an artificial neural network. The NARMA L2 neural controller is used to generate data and for training networks. To obtain the result and compare it with the real-time power plant, data is collected. The input variables provided to the neural network have a large effect on the hidden layer and the output of the neural network. The circuit board used in this research has a DC bridge, a transformer and voltage regulators. The result comparison shows that the integration of artificial neural networks and electric circuits shows enhanced performance with high accuracy of prediction. It was observed that the ANN integration system and electric circuit design have a result deviation of less than 1%. This shows that the integration of ANN improves the performance of turbines.

Grade 8 Students’ Level of Conceptual Understanding of Electric Circuits Using Virtual Manipulative

The challenge to Physics teachers is finding ways to address students’ alternative conceptions and misconceptions. Traditional instruction often fails to change these ideas because students deeply hold them. In this study, we report the effects of using virtual manipulatives on students’ conceptual understanding of the topic, electricity. In learning the concepts on DC circuits, energy, current-voltage-resistance relationship, and potential difference, the students used the Physics Education Technology (PhET) interactive simulations project of the University of Colorado, particularly the Circuit Construction Kit DC Virtual Lab simulation app. The virtual activities that the students conducted were able to augment the class discussion. The results of the post-instruction administration of the assessment instrument, Determining and Interpreting Resistive Electric Circuits Test (DIRECT), revealed that the simulations helped the students analyze the physical aspects of electric circuits. Technology integration in classroom discussion of electric circuits effectively engaged students to learn more about Physics concepts.

Coupling of External Electric Circuits with Computational Domains

Coupling of electrical circuits with 2D and 3D computational domains is very important for practical applications. To this aim, the notions of “electrical current” and “voltage” must be defined precisely and linked with local quantities (i.e., fields and potentials) in the computational domain. Apart from the static case, the definition of voltage is more complex than it may appear at a first glance, and it is usually tainted by unspoken and/or not justified assumptions. The purpose of this work is twofold: on one hand, to shed light on the definition and on the physical meaning of voltage in the case of time varying quasi-static fields and, on the other hand, to show how to establish coupling equations between lumped parameters circuit model and 2D/3D computational domains. It is demonstrated that a precise physical significance can be given to the voltage in terms of power balance only (the notion of potential is unnecessary). A couple of original operators which allow to express voltages and currents are introduced. Based on a critical analysis of the research literature, it is shown that existing coupling formulas can all be rewritten as particular cases of these two operators. The developed analysis is independent from any computational method and can be used to devise new coupling formulas.

Elastic breakdown via multi-core high frequency discharge for lean-burn ignition

An advanced ignition technique is developed to achieve multi-event breakdown and multi-site ignition using a single coil for ignition quality improvements. The igniter enables a unique elastic breakdown process embracing a series of high-frequency discharge events at the spark gap. The equivalent electric circuits and current/voltage equations are identified and verified for the first time to explain the working principle that governs such an elastic breakdown process. Benchmarking tests are first performed to compare the elastic breakdown ignition with the conventional and advanced multi-electrode ignition systems. The elastic breakdown and spark events are thereafter analyzed through current and voltage measurements and high-speed imaging techniques. Finally, ignition tests in combustion chambers are performed to examine the effects on the ignition process in comparison with conventional coil-based ignition systems. The experiments show that, the elastic breakdown ignition can distribute multiple high-frequency breakdown events at all electrode pairs of a multi-electrode sparkplug while using only one ignition coil, thereby offering significant cost saving advantage and packaging practicability.

CONCEPTION D’UN LIVRE NUMÉRIQUE SUR LES CIRCUITS ÉLECTRIQUES ET FORMATION DES ENSEIGNANTS / DESIGN OF A NUMERIC BOOK ON ELECTRIC CIRCUITS AND TEACHER EDUCATION

<p>Dans la présente recherche, nous présentons un résumé des travaux réalisés de par le monde sur la formation scientifique des enseignants des écoles primaires et nous verrons qu’elle est insuffisante pour initier les élèves aux sciences. Ensuite, nous esquissons une synthèse des recherches qui développent des environnements didactiques axés sur l’expérimentation, en vue d’aider les enseignants à acquérir les rudiments de la démarche expérimentale. Finalement, nous illustrons la structure générale d'un livre numérique portant sur l'expérimentation relative aux fonctionnements de circuits électriques simples, suivis de quelques commentaires d'étudiants québécois en formation qui l'ont étudié dans le cadre d'un cours universitaire portant sur la didactique des sciences et des technologies, au primaire.</p><p> </p><p>In this research, we present a summary of the work done around the world on the scientific training of primary school teachers and we will see that their training is deficient. Then, we sketch a synthesis of research that develops didactic environments focused on experimentation, to give teachers, the basics of the experimental approach. Finally, we illustrate the general structure of a digital book on experimentation related to the operation of simple electrical circuits, followed by some comments from Quebec students in training who experimented with it in a university course on the didactics of sciences and technologies at the primary level.</p><p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/edu_01/0975/a.php" alt="Hit counter" /></p>

Features of calculation of characteristics of the compensated induction motor in the matlab simulink software environment

An asynchronous electric motor with a short-circuited rotor is the most common means of converting electrical energy into mechanical energy in the electric drive of working machines in industry and agriculture. Modern methods of increasing the energy efficiency of induction motors with short-circuited rotor are aimed at finding with the help of computer technology the optimal solutions in the processes of their design, production and operation using new high-performance materials in machines. Such methods do not change the physical processes occurring in the induction motor, ie are passive. However, despite numerous improvements and scientific achievements, technical and economic indicators of induction motors still do not meet modern energy requirements. It is necessary to use ways to increase the energy efficiency of induction motors while maintaining their simplicity and reliability. It is proposed to use internal capacitive compensation of reactive power of induction motors. The aim of the research is to develop a mathematical model of an induction motor with internal capacitive reactive power compensation in the MathLab Simulink software environment for the calculation of operating and mechanical characteristics. A mathematical model of an induction motor with internal capacitive reactive power compensation in the MathLab Simulink software environment using the theory of electric circuits has been developed. The developed mathematical model allows to study the working and mechanical characteristics of an induction motor with internal capacitive compensation of reactive power. Numerical researches of characteristics of the induction motor with internal capacitive compensation of reactive power are carried out and their comparison with corresponding characteristics of the basic induction motor is carried out.