Which law describes the relationship between current, voltage, and resistance in an electrical circuit?

• A. Kirchhoff's Law
• B. Ohm's Law
• C. Coulomb's Law
• D. Faraday's Law

Answer: (D)

Ohm's Law explains how current, voltage, and resistance relate in a circuit. It states that voltage across a conductor equals the current through it times its resistance: V = I × R. In other words, current equals voltage divided by resistance: I = V / R. This means increasing voltage increases current, while increasing resistance decreases current, assuming the material behaves ohmically and temperature stays relatively constant.

For example, with a 12-volt source across a 4-ohm resistor, the current is 3 amperes (I = 12 / 4). If the resistance doubles to 8 ohms with the same voltage, the current drops to 1.5 amperes. Some components don’t follow Ohm’s Law exactly at all temperatures or operating conditions, but for many resistors and simple circuits, this linear relationship is what governs how voltage, current, and resistance interact.

Other laws mentioned describe different phenomena: Kirchhoff’s laws deal with current and voltage in complex networks, Coulomb’s Law describes the force between charges, and Faraday’s Law relates changing magnetic fields to induced voltages. The direct V–I–R relationship is specifically Ohm’s Law.