In a series circuit, the total resistance equals the sum of the resistances.

• A. The current is the same through all components
• B. The total resistance equals the sum of the resistances
• C. The voltage drop across each component is the same
• D. The power output of each component is the same

Answer: (B)

In a series circuit, the current flows through every component one after another, so each resistor adds its opposition to the same current. That means the total resistance is simply the sum of the individual resistances, because each resistor contributes its own resistance to the overall path the current must pass through. Using Ohm’s law, the total voltage equals the current times the total resistance (V = I × R total), and since the same current goes through all components, the total resistance must be R total = R1 + R2 + …. For example, 4 Ω and 6 Ω in series give a total of 10 Ω; with 2 A circulating, the supply voltage is 20 V, and the voltage drops are 8 V and 12 V, which add to 20 V. The other statements aren’t about how total resistance works: the current is the same through all components is a property of series circuits but doesn’t define the total resistance by itself; the voltage drop across each component isn’t the same in a series circuit; and the power dissipated by each component isn’t the same unless the resistances are equal.