Kirchhoff's Voltage Law (KVL) and Kirchhoff's Current Law (KCL) are fundamental circuit laws. Which statement correctly describes them with a simple example?

• A. KVL: sum of voltages around any closed loop is zero; KCL: sum of currents entering a node equals the sum leaving; example: loop with a battery and a resistor; node with currents I1, I2, I3.
• B. KVL concerns currents in loops and KCL concerns voltages at nodes; example uses capacitors only.
• C. KVL applies only to DC circuits and KCL applies only to AC circuits.
• D. KVL states power in a loop is zero and KCL states energy at a node is conserved.

Answer: (A)

The main idea is that circuit laws express conservation: energy around a loop and charge at a node must balance.

Kirchhoff's Voltage Law says that if you go around any closed path, the sum of the voltage rises and drops you encounter is zero. This reflects energy conservation as you return to your starting point in potential. A simple loop with a battery and a resistor illustrates this: moving with the loop you gain the battery voltage V and later lose IR across the resistor. The algebraic sum is +V − IR = 0, which gives IR = V. That shows how voltages balance around the loop.

Kirchhoff's Current Law says that at any node, the total current flowing into the node equals the total current flowing out. This is charge conservation at a junction. If currents I1 and I2 flow into a node and I3 flows out, then I1 + I2 = I3 (or, in algebraic form, the sum of currents with signs around the node is zero). This captures the idea that whatever current splits at a junction must come from the currents entering it.

The other statements mix up what each law concerns (current vs. voltage) and when they apply (DC vs. AC), and they introduce notions like power or energy at a node that aren’t what KVL or KCL describe. Both laws apply to both DC and AC circuits and focus on voltages around loops and currents at nodes, respectively.