Up to this point we have analyzed circuits containing only resistors and in dependent current sources. Applying KCL in such circuits is simplified be. cause the sum of currents at a node only involves the output of current sources or resistor currents expressed in terms of the node voltages Adding voltage sources to circuits modifies node analysis procedures because the current through a voltage source is not directly related to the voltage across it. While initially it may appear that voltage sources complicate the situation, they actually simplify node analysis by reducing the number of equations required.