• To develop equations for electrical circuits there are some items to follow,

1. For each component, assume a current flow, then label the current direction, and resulting voltage polarity across each element.

2. Examine the circuit,

- Look for sections where components can be combined to have simpler values.

- Look for elements such as voltage dividers, current dividers, etc.

- Look for nodes where the voltage will be known, apply Kirchof’s current law.

- Look for branches where the current will be known, apply the Voltage law.

- If multiple loops with separate sources exist, use the mesh method.

3. Develop equations

4. Eliminate unwanted values.


• Consider the system below,



• Practice problem,