Correspondence Between Real Electric Circuit and Ohmic Models:Secondary School Students Perspective

النوع : Mémoire

Students studying electricity are confronted with a barrier to developing insightful understanding of direct current (DC) circuit operations. This thesis investigated students’ understanding of DC electric circuit and their ability to apply the laws of voltage and current qualitatively and quantitatively. In particular, it examined: 1) the ability of students to build up a simple closed circuit; 2) students’ understanding of the DC electric current: its direction and flow in series and parallel circuits; 3) students’ ability to sketch a diagram from a real circuit made up of many bulbs and dry cells connected in series or parallel; 4) students’ ability to distinguish among the concepts of voltage, current, power, and energy; 5) students’ understanding of the concept of resistance; and 6) students’ ability to manipulate the variables of a DC electric circuit quantitatively and qualitatively (V, R, I). A paper-and-pencil test was developed and administered to a sample of 300 Lebanese secondary-school students enrolled in the science sections. Only 227 students answered more than 60% of the items and therefore were included in the final analysis. Results obtained revealed that about half the students were unable to light a bulb by connecting the two poles of the cell to the two terminals of the bulb and unable to draw diagrams of real circuits although they were able to draw schematic diagrams. Results also revealed that students have a misconception that a dry cell is a source of constant current and were unable to relate the intensity of the current traversing a bulb to its brightness. Although students knew that the voltage and the brightness change when a lamp is shorted out, they did not recognize that the current also changes. Results also showed that most students were able to solve numerical problems applying Ohm’s law while fewer students can reason and solve conceptual problems. Finally it was recommended that physics teachers pay attention to the practical part of physics and focus on laboratory work where students manipulate dry cells, bulbs and electric appliances in order to decrease the gap between practical physics and class lectures.