In a DC circuit with V = 12 V and R = 4 Ω, what is the current I?

• A. 12 A
• B. 3 A
• C. 4 A
• D. 1 A

Answer: (B)

Current in a DC circuit is found using Ohm’s law: I = V / R. With a 12 V supply and 4 Ω of resistance, the current is 12 divided by 4, which equals 3 A. This reflects how voltage pushes charges and how resistance slows them down. If you changed the resistance while keeping voltage fixed, the current would change inversely; if you increased the voltage, the current would increase proportionally. The other numbers would require different voltage or resistance values (for example, 12 A would need 1 Ω, 4 A would need 16 V, and 1 A would need 4 V).