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

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

Answer: (D)

Ohm's Law relates voltage, current, and resistance. In its simplest expression, voltage equals current times resistance, V = I × R. This form directly shows how voltage depends on how hard charges are pushed (voltage) and how much opposition there is to that push (resistance). If you know any two of the quantities, you can find the third; for example, with 2 A of current and 5 Ω of resistance, the voltage is 10 V.

The other options are valid rearrangements or relate to a different concept: I = V / R and R = V / I come from the same law but are not the direct, most straightforward form. P = V × I gives electrical power, which is a related quantity derived from voltage and current, not the basic voltage–current–resistance relationship.