Which circuit has one path for the current to flow?

• A. Parallel circuit
• B. Series circuit
• C. Flat key
• D. Ball bearings

Answer: (B)

In circuits, the arrangement of components determines how many paths current can take. A single path for current means all components are connected end-to-end in one loop, so there is only one route electrons can follow. In this series setup, the same current flows through every component because there’s nowhere else for the electrons to go. The total resistance is the sum of each component’s resistance, and the current is given by I = V / (R1 + R2 + ...).

If instead there are multiple paths (a parallel arrangement), the current can split among the branches, so different branches may carry different currents, though the voltage across each branch remains equal to the source voltage. The distractors here aren’t electrical paths, so they don’t describe how current flows in circuits.