What is the significance of the power factor being zero in an AC circuit?
**Wattless current** occurs in pure inductor or capacitor, I_rms non-zero but average power zero because φ=±90°, cos φ=0, energy oscillates between source and field, no dissipation, used in choke coil to limit current without heating, unlike resistor where power dissipated. A power factor of zero ( cos Φ = 0 ) means the phase difference between voltage and current is 90°, as in purely inductive or capacitive circuits. This indicates no average power is dissipated, as energy is only stored and released, not consumed. Applying X_L = ωL, X_C = 1/ωC, Z = √(R² + (X_L - X_C)²), I_rms = V_rms/Z, P =
Ref: NCERT > Physics Book > Alternating Currents > Power in AC Circuits - Power Factor and Wattless Current
