Which expression represents Ohm's law?

• A. I = V / R
• B. V = I / R
• C. R = V * I
• D. P = VI

Answer: (A)

Ohm's law shows how voltage, current, and resistance are connected. The core idea is that current flows in proportion to voltage and is limited by resistance. The form V = I R is the standard representation, and solving for current gives I = V / R. This rearrangement means current equals the voltage driving the circuit divided by the resistance the current faces. The units line up too: volts divided by ohms equals amperes, so the relationship makes physical sense. If you raise the voltage across a fixed resistor, the current increases proportionally; if you raise the resistance while keeping voltage the same, the current drops inversely.

The other expressions aren’t Ohm’s law: V = I / R would imply voltage is proportional to current divided by resistance, which doesn’t match the correct V = I R relationship and doesn’t have consistent units. R = V * I would imply resistance equals voltage times current, which is not how resistance is defined (it’s V / I). P = VI describes electrical power, not the direct V–I–R relationship, so it’s related but not an expression of Ohm’s law.