In a series circuit, how is total resistance calculated?

In a series circuit, how is total resistance calculated?

• A. Divided
• B. Multiplied
• C. Subtracted
• D. Added

Answer: (D)

In a series circuit, resistances add because the same current flows through each component. The voltage drop across each resistor is V_i = I × R_i, so the total voltage is the sum of these drops: V_total = I(R1 + R2 + ...). Since V_total = I × R_total, the equivalent resistance must be R_total = R1 + R2 + ... . That’s why total resistance is found by adding the individual resistances. In parallel, the combination is different (reciprocals add), which is why simple addition isn’t used there.

In a series circuit, resistances add because the same current flows through each component. The voltage drop across each resistor is V_i = I × R_i, so the total voltage is the sum of these drops: V_total = I(R1 + R2 + ...). Since V_total = I × R_total, the equivalent resistance must be R_total = R1 + R2 + ... . That’s why total resistance is found by adding the individual resistances. In parallel, the combination is different (reciprocals add), which is why simple addition isn’t used there.