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

• A. R_total = R1 × R2 × ... × Rn
• B. R_total = (R1 + R2 + ... + Rn)^-1
• C. R_total = R1 + R2 + ... + Rn
• D. R_total = 1 / (1/R1 + 1/R2 + ... + 1/Rn)

Answer: (C)

In a series circuit, current has only one path through every component, so each resistor adds its own opposition to the flow. The total resistance is simply the sum of the individual resistances because the current must pass through each one in turn, accumulating the overall resistance. This means R_total = R1 + R2 + ... + Rn. For example, two resistors of 2 ohms and 3 ohms in series give 5 ohms total, affecting the current drawn from the source accordingly. The other forms don’t describe a series arrangement: the reciprocal of the sum applies to circuits in parallel, where multiple paths share the current; a product or the reciprocal of the sum does not reflect how resistances combine in series.