ESCOTO, Richard G. July 30 2010

Black Score

Resistive Inductive and Capacitive Circuits with a Sinusoidal Excitation

From the first part of the experiment, it can be observed that pure resistive circuits have no relationship with the frequency of the sinusoidal voltage. This is true because as frequency is increased, the impedance of the circuit does not change at all. Moreover, based from the table it can be concluded that resistive circuits have constant current flowing through them even though the frequency changes. Furthermore, it can be observed on the oscilloscope that in pure resistive circuits, the voltage and the current waveform are both sinusoidal and both crosses zero at the same time. Hence it can be concluded that the two waveforms are in phase. Noticeably, the current waveform is smaller compared to the voltage waveform. It can also be concluded that the impedance of pure resistive circuits is simply application of series-parallel resistors.

From the second part of the experiment, it can be observed that a capacitive circuit has a direct relationship with frequency. Based from the table, as frequency is increased, the capacitive reactance of a capacitor decreases. This means that a capacitor has a certain response to frequency changes. That is, frequency is inversely proportional to the capacitive reactance. Unlike in DC, a capacitor is said to be open, hence to current flows through it. However, based from the table, it can be concluded that current can flow through a capacitor for as long as the voltage input is AC. Furthermore, it can be concluded that as frequency is increased, the current flowing through the capacitor also increases. Furthermore, it can be concluded that as frequency is increased, the impedance of the circuit decreases. With respect to voltage and current waveform, it can be observed that capacitive circuits are not like resistive circuits. The voltage and the current do not reach zero, maximum point and minimum point at the same time just like in resistive circuits. Hence, the voltage goes to its positive peak when the current zeroes out. It can be observed that in capacitive circuits the current waveform leads goes to its maximum value first before the voltage waveform does.