In a series $LR$ circuit with $X_L = R$, the power factor is $P_1$. If a capacitor of capacitance $C$ with $X_C = X_L$ is added to the circuit, the power factor becomes $P_2$. The ratio of $P_1$ to $P_2$ will be:

The capacitor of an oscillatory circuit is enclosed in a container. When the container is evacuated,the resonance frequency of the circuit is $10\, kHz$. When the container is filled with a gas,the resonance frequency changes by $50\, Hz$. The dielectric constant of the gas is

If the frequency of the $AC$ supply is equal to the resonant frequency,which ammeter will show zero reading?

$A$ series $AC$ circuit consists of an inductor and a capacitor. The inductance and capacitance are $1 \ H$ and $25 \ \mu F$ respectively. If the current is maximum in the circuit,then the angular frequency will be:

Power delivered by the $ac$ source of the circuit becomes maximum when

If the inductance and capacitance are both doubled in an $L-C-R$ circuit,the resonant frequency of the circuit will