Which formula expresses Ohm's Law in its basic form?

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

Answer: (B)

Voltage equals current times resistance. This is Ohm’s law in its simplest expression: V = I × R. It shows how the voltage across a conductor is determined by the current flowing through it and its resistance. For example, if 2 A flows through a 5 Ω resistor, the voltage across it is 10 V (2 × 5).

The other forms don’t represent the basic relationship. V = R / I would set voltage equal to resistance divided by current, which isn’t how voltage and current relate in a resistor. I = V × R would yield current as volts times ohms, which doesn’t match the units (it’s dimensionally incorrect). P = V × I gives power, not the voltage-current-resistance relationship, though it’s related as P = I^2R or P = V^2/R in circuits.