In a series circuit, what is true about current through each component?

• A. The current is the same through all components.
• B. The current doubles through each successive resistor.
• C. The current is inversely proportional to the voltage drop.
• D. The current varies with each component.

Answer: (A)

In a series circuit, the same current flows through every component because there is only one path for the charge to take. The current is set by the total resistance and the source voltage: I = V / R_total. While the current stays the same as it passes through each element, the voltage across each component can differ, with V = I R for each resistor. So if you have two resistors in series, they share the same current I, but the voltages across them are proportional to their resistances and add up to the source voltage. The idea that the current doubles through successive resistors, or that the current is inversely proportional to voltage drop, or that the current varies with each component, conflicts with the one-path nature of a series circuit where current remains constant.