Resumo No presente artigo, apresenta-se o método experimental de determinação da constante de Planck, uma das constantes físicas fundamentais, através do estudo das propriedades quânticas e ondulatórias do diodo emissor de luz (LED) numa maquete experimental automatizada, que contém um circuito eletrônico ligado a um computador utilizando o protocolo USB com o auxílio da plataforma Arduino. Os LEDs têm encontrado diversas aplicações, por exemplo: na iluminação doméstica, pública, nos semáforos, nos monitores de TV, computadores, para ler discos de CD e DVD em unidades de computador e em unidades de console de jogos, ou para transmitir sinais de controles remotos para equipamentos eletrônicos. O LED é uma ligação vital entre eletrônica e fotônica os lasers de semicondutor baseados em LEDs enviam sinais ópticos modulados através de fibras ópticas, atendendo à demanda cada vez maior da telecomunicação de banda larga e Internet. A automatização das medições e da elaboração dos dados dos experimentos de Física permite aos alunos aprofundar o conhecimento de métodos e técnicas do experimento, estudar aparelhos de pesquisa científica, dominar diferentes métodos de pesquisas experimentais, dominar métodos matemáticos e gráficos dos resultados obtidos e também a avaliação das medições realizadas.

Abstract In the present article, the experimental method of determination of Planck's constant, one of the fundamental physical constants, is presented by studying the quantum and wave properties of the light emitting diode (LED), in an automated experimental model which contains an electronic circuit connected to a computer using the USB protocol with the help of the Arduino platform. LEDs have found a variety of applications, for example: in home, public, in-house lighting, TV monitors, computers, to read CD and DVD discs in computer units and game console units, or to transmit signals from remote controls to electronic equipment. LED is a vital link between electronics and photonics: LED-based semiconductor lasers send modulated optical signals through fiber optics, catering to the ever-increasing demand for broadband and Internet telecommunication. The automation of measurements and data processing of Physics experiments allows students to deepen their knowledge of methods and techniques of the experiment, to study scientific research apparatus, to master different experimental research methods, to master mathematical methods and graphs of the results obtained, and also the evaluation of the measurements made.

Abstract: Arbuscular Mycorrhizae (AM) are mutualistic associations between Arbuscular Mycorrhizal Fungi (AMF) and the roots of many plant species. AMF spores give rise to filaments that develop in the root system of plants and contribute to the absorption of water and some nutrients. This article introduces a semi-automated counting model of AMF spores in slide images based on Artificial Neural Network (ANN). The semi-automated counting of AMF spores facilitates and accelerates the tasks of researchers, who still do the AMF spore counting manually. We built a representative database of spore images, processing images through the Circle Hough Transform (CHT) method and training an ANN to classify patterns automatically. The classification analysis and the performances of the proposed method against the manual method are presented in this paper. The accuracy for the identification of spores by CHT in conjunction to ANN classification in the images was 90%. The results indicate that this method can accurately detect the presence of AMF spores in images as well as count them with a high level of confidence.