#### Question

In a series LCR circuit, obtain the condition under which watt-less current flows in the circuit ?

#### Solution

Average power dissipated through a series LCR circuit is given by \[P_{av} = E_v I_v \cos\left( \phi \right)\]

where, *E _{v}*

_{ }= rms value of alternating voltage

*I*= rms value of alternating current

_{v}*Φ*= phase difference between current and voltage

For wattless current, the power dissipated through the circuit should be zero.

\[i . e . , \cos\left( \phi \right) = 0\]

\[ \Rightarrow \phi = \frac{\pi}{2}\]

Hence, the condition for wattless current is that the phase difference between the current and voltage should be π/2 and the circuit is purely inductive or purely capacitive.

Is there an error in this question or solution?

Solution In a Series Lcr Circuit, Obtain the Condition Under Which Watt-less Current Flows in the Circuit ? Concept: Ac Voltage Applied to a Series Lcr Circuit.