The Importance of R Circuit Modeling and Analysis

Andrés Cordero Muñiz

Resistances occur in everyday life and are not limited to the carbon resistors we commonly associate them with. Any device that consumes power can be modeled as a resistor and power sources can be modeled with a battery. In essence, you can model most scenarios of everyday life with a battery in parallel with resistors. Thanks to the easy to analyze nature of DC R circuits, it becomes trivial to measure values such as voltage, current and power.

For example, when you consider the accessories in your car, you get a circuit with a 12-V battery in parallel with resistances for the headlights, radio, each speaker, the ignition, etc. with switches. Everything is in parallel in order to receive the same voltage, and because this way if a light goes out, the rest of the accessories are not affected. If you can get the current provided by the battery, you can calculate the current that goes through your accessories and thus how many watts they consume, or if they specify watts, measure the current and calculate the resistance.

Another easy example is in your home. Things such as light bulbs, washing machines, computers, and your kitchen appliances have wattage ratings so in a model they also look as resistors, since they use up electrical energy and emit heat. By calculating the power draw, you can predict your future power bill and help conserve both energy and save your money.

For R Circuits there are many useful analysis tools, be it Kirchhoff’s Voltage and Current Laws, Current Divisor Equation, Voltage Divisor Equation, Parallel and Series Equivalencies, Wye-Delta transformations, etc. Thanks to Thevenin and Norton’s theorems, you can even model the net effect of a circuit with just a voltage/current source and a resistor!

In conclusion, R Circuits are the most basic type and the easiest to analyze, which is a good thing because they’re the most common model available, which is why Ohm’s Law is so essential in the world of circuits. Make sure you master the analysis of these before moving on to more complex circuit analysis!