In an $L-C-R$ circuit,the power factor at resonance is

At which point is the circuit inductive?

An $LCR$ series circuit of capacitance $62.5 \, nF$ and resistance of $50 \, \Omega$ is connected to an $A.C.$ source of frequency $2.0 \, kHz$. For the maximum value of the amplitude of current in the circuit,the value of inductance is $.......... \, mH$. (take $\pi^2 = 10$)

For better tuning of a series $LCR$ circuit in a communication system,the preferred combination is

$A$ telephone wire of length $200\, km$ has a capacitance of $0.014\, \mu F$ per km. If it carries an $AC$ of frequency $5\, kHz$,what should be the value of an inductor required to be connected in series so that the impedance of the circuit is minimum? (in $mH$)

$A$ resistor of $50 \Omega$,an inductor of self-inductance $\left(\frac{3}{\pi^2}\right) H$,and a capacitor of unknown capacity are connected in series to an a.c. source of $100 \ V$ and $50 \ Hz$. When the voltage and current are in phase,the value of capacitance is (nearly):