Three 3-ohm resistors connected in series have what equivalent resistance?

• A. 9 ohms
• B. 3 ohms
• C. 6 ohms
• D. 27 ohms

Answer: (A)

In a series arrangement, the current through every resistor is the same and the resistances simply add together. Each resistor has 3 ohms, so the total becomes 3 + 3 + 3 = 9 ohms. So the equivalent resistance is nine ohms. The other options jump to different operations or configurations: 3 ohms would be just one resistor, 6 ohms would come from two in series, and 27 ohms would come from multiplying or misapplying the calculation. (For reference, if these were in parallel, the result would be 1 ohm.)