Everton Lüdke

Um experimento para ensino de conceitos de transferência de calor em laboratório de física

In this paper, we present a simple, low-cost experiment for experimental physics in a universty third-year level which allows to corroborate the main fundamental concepts regarding heat transport phenomena and to assess the solutions of the Fourier law in cylindrical coordinates.

REFLEXÕES SOBRE GÊNERO NO ENSINO DE BIOLOGIA: UM OLHAR SOBRE O DISCURSO DE ESTUDANTES DO PRIMEIRO ANO DO ENSINO MÉDIO ACERCA DA GRAVIDEZ NA ADOLESCÊNCIA

Historicamente, o Ensino de Ciencias tem reduzido a abordagem da sexualidade a conhecimentos sobre anatomia e fisiologia de orgaos genitais, bem como sobre a profilaxia de doencas sexualmente transmissiveis, concentrados na disciplina de Biologia. Nesse contexto, a gravidez na adolescencia passa a ser considerada como “indesejada”, reduzindo a possibilidade de dialogo para/com os jovens acerca desse fenomeno. Em contracorrente a esse cenario, desenvolvemos uma pesquisa qualitativa, por meio da utilizacao do documentario “Meninas”, levantando pontos para reflexao entre 51 estudantes do 1o ano do Ensino Medio, de uma escola publica da regiao central do Rio Grande do Sul, Brasil, objetivando tornar explicito o que pensam esses jovens sobre a gravidez na adolescencia. Os resultados, analisados por meio da Analise Textual Discursiva, apontam para um pensamento homogeneo entre esses sujeitos e remetem a uma forma negativa de lidar com a sexualidade, expondo uma profunda desigualdade no tratamento entre generos, imprimindo julgamentos depreciativos em relacao a mulher e a mulher-mae. Assim, convidamos educadores a analisarem os processos que educam individuos como mulheres e homens, sobretudo, se quisermos investir em possibilidades de propor intervencoes que permitam modificar essas relacoes de poder de genero vigentes, contribuindo para um Ensino de Ciencias comprometido com a igualdade social.

HCO+and Radio Continuum Emission from the Star Forming Region G75.78+0.34

We present 1.3 and 3.6 cm radio continuum images and a HCO+ spectrum of the massive star forming region G75.78+0.34 obtained with the Very Large Array (VLA) and with the Berkley Illinois Maryland Association (BIMA) interferometer. Three structures were detected in the continuum emission: one associated with the well-known cometary H ɪɪ region, plus two more compact structures located at 6′′ east and at 2′′ south of cometary H ɪɪ region. Using the total flux and intensity peak we estimated an electron density of ≈1.5 × 104 cm−3, an emission measure of ≈6 × 107 cm−6 pc, a mass of ionized gas of ≈3 M⊙, and a diameter of 0.05 pc for the cometary H ɪɪ region, being typical values for an ultracompact H ɪɪ region. The HCO+ emission probably originates from the molecular outflows previously observed in HCN and CO.

Um experimento hemodinâmico em sala de aula para ensino de biofísica da circulação

In this paper, it is discussed a setup of a suitable experiment to teach fundamental concepts about the biophysics of ultrasonography, aiming at hemodynamical diagnosis and arterial blood flow assessment. It is presented and discussed a sonic transceiver operating at 10 MHz and the methods of doppler echo signal processing and digital analysis employing acoustic analysis softwares to obtain informations about the blood velocity within the right common carotid artery. A suitable methodological approach to carry out an experiment with a student group simulating an actual medical exam is also presented.

Um método para experimentação com baixas capacitâncias

In this paper, I present details of building a capacitance meter for measuring electric capacitance of small metalic objects near to each other. An oscillator employing a single bipolar transistor produces a signal whose period in microsseconds can be measured with a conventional osciloscope and a simple equation allows to derive the capacitance in picofarads. An analysis of the instrumental transfer function shows a suitable experimental accuracy for measurements between 2 and 500 pF. The problem of capacitance measurement for a conductive sphere and a plane is analyzed showing a good agreement between theoretical results and the measurements. Other possibilities for approaching other experimental situations in an electromagnetics teaching lab with students and a discussion of resultas are also presented.

Velocidade do som no ar e efeito Doppler em umunico experimento

Esse artigo explica uma modificacao do classico experimento de medida da velocidade do som vs no ar livre pelo metodo de medida de tempo de propagacao de ondas sonoras captados por dois microfones, a fim de obter melhor precisao nas medidas. Apresentamos circuitos de producao e captacao de sinais de ultra-sons em 40 kHz que permitem, alem de determinar vs com melhor precisao, explorar o efeito Doppler-Fizeau quantitativamente, o que nao pode ser feito com ondas sonoras aud´ iveis. Uma metodologia adequada para trabalhar o experimento com um grupo de alunos de segundo ano de laboratorio de f´ isica geral tambemapresentada. Palavras-chave: velocidade do som, efeito Doppler. This paper explains a modification of the classical experiment of measuring the sound speed vs in free air by using measurements of time delay between two pulses of sound waves detected by two microphones in order to obtain better accuracy of measurements. We present circuits to produce and analyze 40 kHz ultrasound signals which allows not only to determine vs but also to explore the Doppler-Fizeau effect quantitatively, which is not possible with audible signals. A student group methodological approach to explore the experiment is also presented.

Uma análise quantitativa do campo magnético dentro de um meio condutor

Neste artigo, apresentamos detalhes da construcao de um experimento laboratorial destinado a analise quantitativa da inducao magnetica produzido dentro de uma coluna que contem um material condutor. Um magnetometro AC de simples construcao apropriado para as medidas e tambem apresentado. A analise numerica dos dados mostra uma aproximacao muito boa com as previsoes teoricas das equacoes de Maxwell aplicadas a eletrodinâmica classica.

Estudando campos elétricos de linhas trifásicas pelo método da cuba eletrolítica

In this paper, we discuss a simple experimental setup to be employed by laboratories aiming academic teaching in electromagnetism, as a support material to investigate electric fields due to three phase lines, employing the classical method of potential analysis of electrolytic trays. The experiment shows that it is possible to gather information regarding safety in working conditions and the exposition of technical staff and workers to electrical fields, as well as to perform further studies of the possible environmental impact of power lines used by electrical energy distribution networks between cities.

Use of resonance strings for physical teaching

In this paper, we discuss a low-cost teaching laboratory experiment to undertake a study of standing waves theory in metal strings. By using a straightforward electronical apparatus based on the electromagnetic feedback we were able to assess quantitatively the harmonic behaviour of standing waves as well as the numerical relationships available from excited oscillation modes.We propose a discussion on the concept of phase velocity and the way the speed of light is introduced in high-school physics. A method for measuring the phase velocity of electromagnetic waves is experimentally developed.

Uso da ressonância em cordas para ensino de física

In this paper, we discuss a low-cost teaching laboratory experiment to undertake a study of standing waves theory in metal strings. By using a straightforward electronical apparatus based on the electromagnetic feedback we were able to assess quantitatively the harmonic behaviour of standing waves as well as the numerical relationships available from excited oscillation modes.We propose a discussion on the concept of phase velocity and the way the speed of light is introduced in high-school physics. A method for measuring the phase velocity of electromagnetic waves is experimentally developed.