Which statement defines Kirchhoff's Current Law?

Which statement defines Kirchhoff's Current Law?

• A. The algebraic sum of currents around a closed loop is zero.
• B. The voltages around a node sum to zero.
• C. The algebraic sum of currents at a node equals zero; currents into the node equal currents out.
• D. The sum of power in a circuit remains constant.

Answer: (C)

Kirchhoff's Current Law is about charge conservation at a junction: the total current entering a node must equal the total current leaving the node. In mathematical terms, if you assign a sign to each branch current, the algebraic sum at that node is zero. This reflects that no charge accumulates at the node, so all incoming currents must be balanced by outgoing currents. This makes the statement that the algebraic sum of currents at a node equals zero, with currents into the node equal to currents out, the best description. The other ideas mix concepts: summing currents around a closed loop is not what KCL states (that would relate to currents vs. loops in a way that isn’t correct), summing voltages around a node isn’t a defined principle, and the total power staying constant is a different energy conservation concept.

Kirchhoff's Current Law is about charge conservation at a junction: the total current entering a node must equal the total current leaving the node. In mathematical terms, if you assign a sign to each branch current, the algebraic sum at that node is zero. This reflects that no charge accumulates at the node, so all incoming currents must be balanced by outgoing currents.

This makes the statement that the algebraic sum of currents at a node equals zero, with currents into the node equal to currents out, the best description. The other ideas mix concepts: summing currents around a closed loop is not what KCL states (that would relate to currents vs. loops in a way that isn’t correct), summing voltages around a node isn’t a defined principle, and the total power staying constant is a different energy conservation concept.