Question
A voltage V = V0 sin ωt is applied to a series LCR circuit. Derive the expression for the average power dissipated over a cycle.
Under what condition (i) no power is dissipated even though the current flows through the circuit, (ii) maximum power is dissipated in the circuit?Solution
Voltage V = Vo sin 
t is applied to an LCR series circuit.
Current is lagging with respect to the voltage applied.
Therefore,
Current in the circuit is given by,
is the phase lag of the current w.r.to voltage applied.Instantaneous Power dissipation is given by, 
