What is the basic equation of Ohm's Law?

• A. P = V × I
• B. E = I × P
• C. V = I × R
• D. R = V ÷ I^2

Answer: (C)

Voltage equals current times resistance. This fundamental relationship shows that the voltage across a conductor drives the current, and the amount of current is determined by how easily the material allows it to flow (the resistance). In one simple form, V = I × R, you can find any one quantity if you know the other two: I = V / R or R = V / I. That’s why this form is considered the basic statement of Ohm’s Law. The other options reference related ideas: power relates to voltage and current as P = V × I, and you can rewrite Ohm’s law to express power in terms of resistance (P = I^2R or P = V^2/R). The expression R = V ÷ I^2 isn’t a valid form of Ohm’s relationship. So the correct, simplest representation is V = IR.