In a series circuit, which variable is not additive?

In a series circuit, current remains constant throughout the circuit, meaning that the same amount of current flows through each component in the circuit. This is a fundamental characteristic of series circuits and emphasizes how current does not vary from one part of the circuit to another.

In contrast, voltage is additive in a series circuit; the total voltage across the circuit is the sum of the voltage drops across each component. Similarly, resistance in a series circuit is also additive, as the total resistance is the cumulative sum of the resistances of all the components. Power, while it can be calculated using the total voltage and current in the circuit, is also dependent on the individual components and can be considered additive as well since it can be calculated based on the collective voltage and current.

Understanding that current does not change in a series circuit highlights the nature of series connections, where each component affects the total voltage and resistance but does not alter the flow of current, making current the non-additive variable in this context.