In a simple series circuit, which statement about total resistance is correct?

In a simple series circuit, which statement about total resistance is correct?

• A. It multiplies the resistances of all components.
• B. It equals the resistance of the last component only.
• C. It is the sum of the resistances of all components.
• D. It is the average of the resistances.

Answer: (C)

In a simple series circuit, all components carry the same current, and each component’s resistance adds to oppose that current. That means the total resistance is the sum of all the individual resistances, because every resistor contributes to the overall opposition to the current. For example, two resistors of 4 ohms and 6 ohms in series give a total of 10 ohms, so the circuit behaves as if a single 10‑ohm resistor is in the path. The current is then determined by V = I R total, so I = V / 10 in that case. Multiplying resistances would not reflect how the voltage drops accumulate in series. Using only the last component’s resistance ignores the others, and averaging wouldn’t account for each resistor’s contribution to the total drop. The sum of all resistances correctly represents the total opposition to current in a series arrangement.

In a simple series circuit, all components carry the same current, and each component’s resistance adds to oppose that current. That means the total resistance is the sum of all the individual resistances, because every resistor contributes to the overall opposition to the current. For example, two resistors of 4 ohms and 6 ohms in series give a total of 10 ohms, so the circuit behaves as if a single 10‑ohm resistor is in the path. The current is then determined by V = I R total, so I = V / 10 in that case.

Multiplying resistances would not reflect how the voltage drops accumulate in series. Using only the last component’s resistance ignores the others, and averaging wouldn’t account for each resistor’s contribution to the total drop. The sum of all resistances correctly represents the total opposition to current in a series arrangement.