Two 5-ohm resistors in series total resistance?

Two 5-ohm resistors in series total resistance?

• A. 5 Ohms
• B. 10 Ohms
• C. 2.5 Ohms
• D. 20 Ohms

Answer: (B)

In a series circuit, resistances simply add together. The same current flows through both resistors, and the total opposition to current is the sum of each resistor’s resistance. So two 5-ohm resistors in series give 5 + 5 = 10 ohms. The other numbers don’t fit the series rule: 5 ohms would occur if only one 5-ohm resistor were present (or if the two were arranged in parallel, where their resistances combine differently). 2.5 ohms is the parallel result of two 5-ohm resistors, not series. 20 ohms would require four 5-ohm resistors in series, not two.

In a series circuit, resistances simply add together. The same current flows through both resistors, and the total opposition to current is the sum of each resistor’s resistance. So two 5-ohm resistors in series give 5 + 5 = 10 ohms.

The other numbers don’t fit the series rule: 5 ohms would occur if only one 5-ohm resistor were present (or if the two were arranged in parallel, where their resistances combine differently). 2.5 ohms is the parallel result of two 5-ohm resistors, not series. 20 ohms would require four 5-ohm resistors in series, not two.