Frequency of $L-C$ circuit is $f_{1} .$ If a resistance $R$ is also added to
it, the frequency becomes $f_{2}$. The ratio of $\frac{f_{2}}{f_{1}}$ will be

One $10\, \,\,V, 60\, W$ bulb is to be connected to $100\, V$ line. The required induction coil has self inductance of value $(f = 50\,Hz)$

A $120\, volt$ $ac$ source is connected across a pure inductor of inductance $0.70 \,henry.$ If the frequency of the source is $60\, Hz$, the current passing through the inductor is

In $LR$ circuit the current increases to one fourth of its maximum value in $4\,sec$, then the time constant of the circuit is

In an $AC$ circuit the potential differences across an inductance and resistance joined in series are respectively $16\,V$ and $20\,V$. The total potential difference of the source is……….$V$