O conceito de potência elétrica: uma intervenção pedagógica para o ensino médio

Abstract

This paper describes and evaluates the application of a pedagogical intervention that includes activities focused on learning concepts related to the study of electrical circuits, especially those of power and electric power, using theoretical introduction texts, computer simulations, experimental and contextualized activities. The proposition was developed in Physics component curricular classes in a 3rd grade Polytechnic High School class from E.E.E.M. Luiz Maria Ferraz – Ciep – in Bagé/RS. The aim is to promote learning related to the association of resistors in series, in order to make the student comprehend that: i) the intensity of the current circulating through the circuit components is the same; ii) the equivalent resistance of the circuit increases when one more resistor is associated in series; iii) the sum of the potential differences between the ends of the resistors is equal to the potential difference applied between the ends of the source; iv) the difference in potential in a resistor is proportional to the intensity of the electric current and the electric resistance; v) it is necessary to treat the circuit as a system; vi) the electric power is directly proportional to the product of the potential difference by the intensity of the electric current; vii) the electricity consumption is directly proportional to the electric power of the device by the time of use. The present study is theoretically well-founded in the Significant Learning Theory, of David Ausubel. The activities has been developed from the previous knowledge of the students involved on a research about the matter in question and during the pedagogical intervention, has been presented moments of progressive differentiation and integrative reconciliation. The educational production has made in a Didactics Sequence form, divided into four teaching modules. On the first module, it has proposed an evaluation and an example of a practical and experimental activity to identify the previous knowledge of the students about Electricity and Electrical Circuits thematic. On the second module, we used theoretical introduction texts with fixation exercises, examples of computer simulation and experimental activities in order to exploit the characteristics of an association of resistors in series. On the third module, it has been used theoretical introduction texts and experimental activities in order to exploit the concepts of electric power and electric energy consumption. On the fourth module, was found the assessment, answered by the students, to collect evidences if has occurred a significant learning of the content. At the end of the module, was proposed an activity to contextualize Physics present in daily life, in which we deepen the understandings about physical concepts of electrical power and electric energy consumption. Through this activity, we suggest a reflection regarding the equipments that use electric energy, providing opportunities to the students to think if they really need all of the equipments or if it is possible to decrease its time use. The results highlighted that the learning aims proposed were achieved through the application of the Didactics Sequence. The students recognized the physical quantities in an electrical circuit, as well as the relation between them, being capable of understanding the electric power concept and demonstrating abilities in calculate the electric energy consumption, which made possible reflections regarding the use of electric equipments. The developed work are synthesized on the educational production, attached to this essay, and it is constituted as a support material (theoretical introduction, computer simulation, experimental and practical activities) to teachers of the Curricular component of Physics in High School, in teaching of electrical circuits.