In an a.c. circuit containing $L, C$ and $R$ in series,the ratio of apparent power to the true power is ($Z$ and $R$ are the impedance and resistance respectively,$\phi$ = phase angle).

In the following circuit,the emf of the source is $E_0 = 200 \, V$,$R = 20 \, \Omega$,$L = 0.1 \, H$,and $C = 10.6 \, F$. If the frequency is variable,then the current at frequency $f = 0$ and $f = \infty$ is:

Which of the following components of an $L-C-R$ circuit,with an $AC$ supply,dissipates energy?

An inductance of $\frac{300}{\pi} \text{ mH}$,a capacitance of $\frac{1}{\pi} \text{ mF}$ and a resistance of $20 \ \Omega$ are connected in series with an a.c. source of $240 \text{ V}, 50 \text{ Hz}$. The phase angle of the circuit is

The impedance of the given circuit is......$\Omega $

How does the sign of the phase angle $\phi$,by which the supply voltage leads the current in an $LCR$ series circuit,change as the supply frequency is gradually increased from very low to very high values?