A series L C R circuit is connected to an ac voltage source. When L is removed from the circuit, the phase…
A series circuit is connected to an ac voltage source.
When is removed from the circuit, the phase difference between current and voltage is .
If instead is removed from the circuit, the phase difference is again between current and voltage. The power factor of the circuit is:
zero
Solution
As phase angle contribution by capacitor and inductor are equal in magnitude, so
$\begin{aligned}
X_{L}=X_{c} \\
\Rightarrow \omega L=\frac{1}{\omega C}
\end{aligned}$
It means that the RLC circuit is in resonance condition.
So, impedance at resonance, \(Z=\sqrt{R^2+\left(X_L-X_C\right)^2}=\sqrt{R^2+\left(X_L-X_L\right)^2}=\sqrt{R^2}=R\)
Thus, power factor, \(\cos \phi=\frac{R}{Z}=\frac{R}{R}=1\)