Which expression gives resistance in terms of voltage and current?

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

Answer: (D)

Resistance is how strongly a component slows down the flow of current. Ohm’s law ties voltage, current, and resistance together: R equals the voltage across the element divided by the current through it. So the correct expression is R = V / I. This captures the idea that for a given resistance, increasing the voltage increases the current proportionally, and for a given voltage, increasing the current requires less resistance.

If you multiply voltage by current, you get power, not resistance, so that form isn’t about resistance. Taking the ratio I / V would describe a quantity related to conductance (the reciprocal of resistance) rather than resistance itself.