In a simple series circuit, if the current is 3.0 A and the voltage across the circuit is 24.0 V, what is the resistance?

• A. 72.0 ohm
• B. 8.0 ohm
• C. 0.125 ohm
• D. 27.0 ohm

Answer: (B)

Ohm's law links voltage, current, and resistance: V = I × R. So resistance equals voltage divided by current. With 24.0 V and 3.0 A, R = 24.0 ÷ 3.0 = 8.0 ohms. A current of 3.0 A through 8.0 ohms would indeed produce 24.0 V, which matches the given data. The other values would require different voltages for the same current (for example, 72.0 ohms would need 216 V, 0.125 ohms would give 0.375 V, and 27.0 ohms would need 81 V).