Question

What is wattless current?

Answer 1

When in any circuit only an inductor or capacitor is connected then power consumption is zero in that circuit this is called wattles current which does not consume any energy in circuit.

Step by step solution:
The current in an AC circuit is said to be Wattles Current when the average power consumed in such a circuit corresponds to Zero. Such current is also called as Idle Current
An AC circuit containing either capacitor or inductor current is said to wattles if the average power consumed in the circuit is zero. The formula used for calculating the wattles current is:
$\Rightarrow P = VI\cos \theta$
Where,
$P \Rightarrow$ Is the power in Watts
$I \Rightarrow$ Is the current in Amperes
$V \Rightarrow$ Is the voltage in Volts
When in the circuit only inductor or capacitor present in that condition the phase difference between voltage and current is $\dfrac{\pi }{2}$
So the power consumption can be calculate by above formula
$\Rightarrow P = VI\cos \left( {\dfrac{\pi }{2}} \right)$
We know $\cos \left( {\dfrac{\pi }{2}} \right) = 0$
So power consumption is
$\Rightarrow P = VI\left( 0 \right)$
$\Rightarrow P = 0 watt$
So we can clearly see that there is no power consumption when phase difference is $\left( {\dfrac{\pi }{2}} \right)$ so this is called wattles current

Note:
When in any AC circuit there is only capacitor then current leads voltage by $\dfrac{\pi }{2}$ phase angle and when in circuit there is only inductor the current lags voltage by $\dfrac{\pi }{2}$ so in both types of pure L and pure C circuit have phase difference same $\dfrac{\pi }{2}$
So in these types of AC circuit power consumption by circuit is zero