THE STUDY OF THE TRANSIENT REGIME IN ELECTRIC CIRCUITS WITH EXCEL SPREADSHEETS

This paper focuses on the use of Excel spreadsheets in the study of the transient regime in electric circuits. Two relevant didactic tools, which have been created with the help of spreadsheets, are presented for the study of the transient regime in a circuit with resistance and capacitance connected in series. With the aid of the first tool we can simulate the charging and discharging of a capacitor. By changing the input data we can easily track how the charging and, respectively, the discharging curves change for the electric charge of the capacitor, the voltage across the capacitor and the current through the circuit. The significance of the time constant. for the RC circuit is emphasized in graphs. The energetic characterization of the transient regime is done through a graph presenting the energy variation in time, from the capacitor, and the energy dissipated in the resistor. For a comparative analysis a graph is drawn, overlaying the curves of the time dependence in case of the capacitor voltage from three different RC circuits. The second tool has been conceived to process the data in the didactic experiment to study the process of discharging of a capacitor on a resistor. The voltage on the capacitor terminals measured during the discharging process is compared to the Voltage calculated with the exponential variation law of the process. From the discharging curve we can determine the capacitance of the capacitor and, thus, certain experimental results are presented. The two previously described tools prove the facilities offered by spreadsheets in conceiving interactive Physics lessons. On the one hand, the possibility to simulate some physical phenomena is highlighted; on the other hind, it is shown that spreadsheets can be successfully used in the processing of experimental data.