where "V" denotes voltage in phasor form, with the amplitude as rms, and "I" denotes current in phasor form, with the amplitude as rms. Also by convention, the complex conjugate of "I" is used, which is denoted formula_3 (or formula_4), rather than "I" itself. This is done because otherwise using the product V I to define S would result in a quantity that depends on the reference angle chosen for V or I, but defining S as V I* results in a quantity that doesn't depend on the reference angle and allows to relate S to P and Q.