NEIEP Mechanics Practice Exam

What remains constant throughout a series circuit?

1. Voltage

2. Resistance

3. Current

4. Power

The correct answer is: Current

In a series circuit, the current flowing through each component remains constant. This is because there is only one path for the electrical flow to take. As a result, all components share the same current. When current reaches various components (like resistors, capacitors, or other devices), it does not split or change; rather, it passes through each one in sequence. This is a fundamental characteristic of series circuits and is defined by Kirchhoff's First Law, which states that the total current entering a junction must equal the total current leaving the junction. While the voltage across individual components may vary depending on their resistance, the total voltage supplied by the source is divided among these components. Similarly, the total resistance of the circuit is the sum of the resistances of the individual components. Therefore, both voltage and resistance can change, but the current remains consistent throughout the circuit. Power, too, can vary based on voltage and current conditions across the individual components.