In the first article in this series, we discussed series circuits that had a fixed load resistance value, regardless or whether the load was ON or OFF. This made calculations of circuit characteristics with fixed load resistances a cut and dried affair. If the circuit is performing normally, voltage readings, voltage drops, and load current calculated with Ohm’s Law, are the actual values that will be found if the circuit is measured while the load is turned ON. However, some components do not have the same resistance value when they are ON. Their resistance either increases or decreases when they are ON. These components are said to have dynamic resistance. Voltage and current measurements of components that exhibit dynamic resistance will not jive with calculated values if we insert the component’s OFF resistance into the Ohm’s Law equation. What’s the reason?