Mnemonic expression for remembering what the variables represent in Ohm's Law for electrical calculations. I=A, Intensity (Current)=Amperes E=V, Electromotive Force=Volts R=O, Resistance=Ohms P=W, Power=Watts See also "PIE in your EIR". P=IE. E=IR. Remembering the above allows one to solve algebraically almost any electrical equation. For the same, expressed in a different way, see PIER=WAVO.