Which equation expresses current in terms of voltage and resistance according to Ohm's Law?

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

Answer: (A)

Ohm's Law shows how current, voltage, and resistance relate to each other. It starts with V = I R, meaning the voltage across a component equals the current through it times its resistance. To express current in terms of voltage and resistance, solve for I by dividing both sides by R, giving I = V / R. This form directly shows how current changes with voltage and resistance: increasing voltage increases current, while increasing resistance decreases current, assuming the other variable stays the same. For example, with 10 V across 2 Ω, the current is 5 A.

The other expressions don’t put current in terms of voltage and resistance: V = I R writes voltage in terms of current and resistance, not current in terms of the two; R = V / I writes resistance in terms of voltage and current; and I = R / V would not align with Ohm’s Law. Dimensional check also supports I = V / R, since volts divided by ohms yields amperes.