In a series circuit, how does the total resistance relate to the individual resistances?

• A. It is the product.
• B. It remains the same as the largest resistor.
• C. It is the sum of individual resistances.
• D. It is the average.

Answer: (C)

In a series circuit, total resistance is the sum of the individual resistances. The same current flows through every component, so each resistor adds its opposition to the path. That means the overall opposition to current is simply the sum of all resistances.

Ohm’s law links this to voltage: for a fixed supply, a larger total resistance lowers the current, and the voltage from the source is shared across the resistors in proportion to their resistance, with all the voltage drops adding up to the source voltage. For example, two equal resistors in series give a total of twice their value (4 Ω + 4 Ω = 8 Ω). With a 12-volt source, the current is 12/8 = 1.5 A, and each resistor drops 6 V.

The other ideas don’t fit this setup: a product of resistances would describe a different, not-series, relationship; staying the same as the largest resistor ignores the added opposition from the others; averaging the resistances underestimates the total resistance amount.