Which formula correctly expresses current in terms of voltage and resistance?

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

Answer: (B)

Ohm's law shows how current depends on voltage and resistance: current is the driving voltage divided by the opposition to flow (the resistance). So the correct expression is current equals voltage divided by resistance. If voltage is labeled as E in a given set, then I = E / R expresses the same relationship. The other forms don’t reflect this inverse relation: I = R / E reverses the ratio, I = E * R multiplies voltage by resistance, and I = V / I is self-referential and not a direct one-step expression of how V and R determine I.