1 of 6 ECE 322 Lab Session 1 The effect of capacitor and inductor in simple RL and RC circuit Resistors, capacitors and inductors are the basic building blocks in linear circuits. Here we look at their real characteristics from the electromagnetic point of view, and the way they can affect circuit performance. All real passive linear electrical components behave like combinations of resistors, capacitors, and inductors. For example, a packaged inductor can be represented realistically by an ideal inductor, along with a capacitor that represents capacitance between the windings, and a resistor that represents the loss in the wire. This is then called a model of an inductor. Modeling is very important for engineers; without good component models, circuit and systems cannot be designed accurately, or at all. The purpose of this lab is to understand the characteristic behavior of resistors (R), capacitors (C) and inductors (L). We do this on the simple examples of RL and RC circuits and their response to a step function excitation. Equipment and parts: oscilloscope (Agilent 54621A or similar); - function generator (Agilent 33120A or similar); - breadboard, resistors, capacitors, inductors, jumper wires. Consider the following circuit: Vs Prelab exercise RC circuit R 2 0 Figure 1: Series RC circuit for experiment 1 Let's write Kirchhof Voltage Law for the circuit above: V = UR+UC The relation between voltage and current at the capacitor is: i = C dU dt If we express UR = iR according to Ohm's law and plug (2) into (1), we get: V=RCdUc dt +Uc (1) (2) (3)