To determine the equivalent resistance of complex circuits, one can apply Ohm's Law and Kirchhoff's Laws, which are essential for analyzing series and parallel configurations. In series circuits, the current remains constant, while in parallel circuits, the voltage across each resistor is the same. For example, in a circuit with an 8.8 ohm and a 4.4 ohm resistor in series, the potential difference across the battery can be calculated using the known voltage across the 4.4 ohm resistor and the total resistance. Similarly, combining resistors in parallel requires calculating the total resistance before determining the current and potential differences. Understanding these principles is crucial for solving complex circuit problems effectively.