Wattless Current
The component of alternating current that is 90 degrees out of phase with AC voltage, consuming zero net electrical power.
Governing formula
I_wattless = I_rms sin φ
SI unit
A (Amperes)
In depth
In purely inductive or capacitive AC circuits (φ = 90°), current flows back and forth exchanging energy with field storage without net energy dissipation (P = V I cos(90°) = 0).
Examples in the real world
AC current flowing through an ideal pure inductor coil or capacitor.