The voltage law that states that the total voltage of a series circuit is equal to the sum of all the voltage drops is

• A. Kirchhoff's Law
• B. Ohm's Law
• C. Thevenin's Law
• D. Watt's Law

Answer: (A)

Kirchhoff's Voltage Law says that the sum of all voltages around a closed loop must equal zero, reflecting energy conservation. In a series circuit the same current flows through every element, and the voltages across each component add up to the source voltage. So the voltage supplied by the source equals the sum of the voltage drops across each component. For example, if a 12 V source feeds two resistors in series and the drops across them are 7 V and 5 V, those drops add up to the source voltage, 12 V, with the current being the same through both resistors. The other laws describe different relationships: Ohm's Law links voltage, current, and resistance for a single element; Thevenin's Law relates a network to an equivalent simplification; Watt's Law is about power, P = VI.