In a series circuit, what remains constant at all points?

• A. Voltage
• B. Resistance
• C. Current
• D. Power

Answer: (C)

In a series circuit, the current remains constant at all points. This is a fundamental characteristic of series circuits, stemming from the principle that there is only one path for current to flow. Since charge cannot accumulate anywhere in the circuit due to the series connection, the same amount of current must pass through each component sequentially.

When analyzing other aspects of the circuit, it's essential to understand that voltage does not remain constant. Instead, it can vary across different components depending on their resistance, following Ohm's law. Additionally, while resistance may remain constant for individual components, the total resistance of the circuit is the sum of the resistances of each component, which can change if more components are added or removed. Power, on the other hand, can vary depending on how the voltage and current interact at different points in the circuit. Thus, in a series circuit, the only quantity that remains unchanged throughout is the current.