In a series circuit, the total voltage equals the sum of the voltages across each component.

• A. True.
• B. False.
• C. Only if resistors equal.
• D. Only if current is zero.

Answer: (A)

In a series circuit, the same current flows through every component, and the source provides a fixed emf. The electric potential must return to its starting value after looping through the circuit, so the voltage drops across each component must add up to the source voltage. This is Kirchhoff’s voltage idea in action: the total voltage equals the sum of the individual voltage drops, regardless of how those drops are distributed among components. Since each component obeys V = I R with the same current I, the total drop is V_total = V1 + V2 + V3 + …, and this sum already accounts for how big each drop is. The magnitudes add regardless of whether resistors are equal, and it doesn’t require zero current.