Which statement expresses Kirchhoff's Current Law?

Which statement expresses Kirchhoff's Current Law?

• A. The algebraic sum of currents entering a node equals the algebraic sum of currents leaving the node.
• B. The total resistance around a loop equals zero.
• C. The product of current and resistance equals voltage.
• D. Power in a circuit is equal to the current times the voltage.

Answer: (A)

At a junction where wires meet, charge cannot accumulate, so the currents must balance. Kirchhoff's Current Law expresses this by saying the algebraic sum of currents entering a node equals the algebraic sum of currents leaving the node. If you treat currents into the node as positive and currents leaving as negative, the total sum is zero. This is the best choice because it directly embodies the conservation of charge at a connection point. For example, if two currents flow into a node and one flows out, the sum of the entering currents equals the leaving current. The other statements describe different electrical relationships: one refers to the sum of voltages around a loop (Kirchhoff's Voltage Law), another is Ohm's law (voltage equals current times resistance), and the last expresses electric power (power equals voltage times current).

At a junction where wires meet, charge cannot accumulate, so the currents must balance. Kirchhoff's Current Law expresses this by saying the algebraic sum of currents entering a node equals the algebraic sum of currents leaving the node. If you treat currents into the node as positive and currents leaving as negative, the total sum is zero.

This is the best choice because it directly embodies the conservation of charge at a connection point. For example, if two currents flow into a node and one flows out, the sum of the entering currents equals the leaving current.

The other statements describe different electrical relationships: one refers to the sum of voltages around a loop (Kirchhoff's Voltage Law), another is Ohm's law (voltage equals current times resistance), and the last expresses electric power (power equals voltage times current).