: The principle of superposition is applicable only for linear systems. The principle of superposition has the ability to reduce a complicated problem to several easier problems each containing only a single independent source. The theorem states as follows: in any linear circuit containing multiple independent sources, the current or voltage at any point in the network may be calculated as algebraic sum of the individual contributions of each source acting alone. When determining the contribution due to an independent source, we disable all the remaining independent sources. That is, all the remaining voltage sources are made zero by replacing them with short circuits, and all remaining current sources are made zero by replacing them with open circuits. Also, it is important to note that if a dependent source is present; it must remain active (unaltered) during the process of superposition. Superposition is a fundamental property of linear equations and, therefore, can be applied to any effect that is linearly related to the cause. That is, the superposition principle applies only to the current and voltage in a linear circuit but it cannot be used to determine power because power is a non-linear function.