Wattless current is the current in a purely inductive or capacitive circuit for which power factor is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → zero
The average power in an AC circuit is
\( \displaystyle P = V_{\mathrm{rms}}\, I_{\mathrm{rms}} \cos\phi \)
where \( \cos\phi \) is the power factor. In a purely inductive or purely capacitive circuit the current and voltage differ in phase by \( \phi = 90^\circ \), so
\( \displaystyle \cos 90^\circ = 0 \)
The current flows but the average power is zero, which is why it is called a wattless current.
NCERT (2026-27):
Power in AC Circuit: The Power Factor – “… The quantity cos φ is called the power factor. … Case (ii) Purely inductive or capacitive circuit: If the circuit contains only an inductor or capacitor, we know that the phase difference between voltage and current is π/2. Therefore, cos φ = 0, and no power is dissipated even though a current is flowing in the circuit. This current is sometimes referred to as wattless current.”