A Level Physics Practice Exam

In a parallel circuit, what remains constant throughout the circuit?

1. Current

2. Voltage

3. Resistance

4. Power

The correct answer is: Voltage

In a parallel circuit, the voltage remains constant across all components connected in that circuit. This is a fundamental characteristic of parallel circuits, resulting from the way they are wired. All components have the same potential difference applied across them, meaning that regardless of the number of branches or components, the voltage experienced by each one remains equal to the total voltage supplied by the source. While the current may vary in accordance with the resistance of each branch (as per Ohm's law), the voltage does not change throughout the circuit. Therefore, it is accurate to state that the voltage is the quantity that remains constant in a parallel arrangement. In contrast, current can differ between branches, resistance can vary based on the configuration, and power can change depending on the voltage and current in each branch. Thus, voltage being constant is the key characteristic of parallel circuits.