First-Order and Second-Order Circuits

Inductors and capacitors are considered energy storage elements. These elements store energy when connected to the source and release energy through a resistor element. The first-order circuit is related to the first-order differential equation. This first-order differential equation can be obtained using RC and RL with and without source. Similarly, the second-order circuit is associated with the second-order differential equation which can be obtained using R, L and C with and without the source. These types of circuits are used in DC motors to control the speed including the field and armature control. Several combinations of these elements can also be used in the magnetic contactor, relay, filter etc. Detailed characteristics of RC, RL and RLC will be discussed in this chapter.