A 12-volt source is connected to a 5-ohm resistor. What is the current?

• A. 2.4 A
• B. 0.96 A
• C. 4.8 A
• D. 12 A

Answer: (A)

Current in a circuit comes from Ohm’s law: I = V/R. With a 12-volt source and a 5-ohm resistor, the current is 12 divided by 5, which equals 2.4 amperes. The magnitude is 2.4 A, and the direction depends on the assumed polarity, but the amount flowing through the resistor is 2.4 A. This also implies the power dissipated by the resistor is P = I^2R = (2.4)^2 × 5 = 28.8 watts. The other numerical options would require different resistance values: for example, 0.96 A would imply about 12.5 Ω, 4.8 A would imply about 2.5 Ω, and 12 A would imply about 1 Ω.