In a series circuit, the current entering a node equals the current exiting.

• A. Greater
• B. Equal
• C. Less
• D. Not Related

Answer: (B)

Conservation of current at a junction is the key idea. In a series circuit there’s only one path for the current, so the same amount of charge flows through every component. At any node where wires meet, the current that enters must also leave—there’s nowhere for the charge to accumulate or to split. That means the current entering a node equals the current exiting.

If the current were larger or smaller at the node, charge would accumulate or disappear, which doesn’t happen in a steady state. And “not related” doesn’t fit here because current at a node is precisely what the circuit’s balance is about.