In a series circuit, the _____ is equal to the sum of the voltage drops across all the resistors.

• A. Applied voltage
• B. Current flow
• C. Resistance
• D. Power

Answer: (A)

In a series circuit, the voltage supplied by the source is distributed across the components, and the voltage drops across each resistor add together to equal that total supply voltage. This is a direct consequence of energy conservation around the loop (Kirchhoff's Voltage Law): the sum of all voltage drops must match the applied voltage. So, the blank is filled by the applied voltage. The other ideas don’t fit this relationship: the current is the same through every resistor in a series circuit, not the sum of the drops; resistance determines how large each drop is but isn’t the total of the drops; and power describes the rate of energy transfer, not the sum of voltage drops.