Which equation expresses Ohm's law?

• A. V = I × R
• B. V = I / R
• C. I = V × R
• D. R = V × I

Answer: (A)

Ohm's law describes how voltage, current, and resistance relate: the voltage across a conductor equals the current through it times its resistance. The standard form is V = I × R, which clearly shows how increasing either current or resistance requires a proportional increase in voltage. Units align as volts = amperes × ohms, making this form intuitive for design and analysis. You can also rearrange to I = V/R or R = V/I, which are other valid expressions of the same relationship. The other proposed forms mix the variables incorrectly—V = I / R, I = V × R, and R = V × I—because they don’t reflect the correct proportional relationships or units.