Out of the following graphs, the correct graphical relation for LC parallel resonant circuit at resonance is

The frequency of oscillation of LCR series circuit is ' $F$ '. The value of capacitance is tripled, then new frequency becomes ' xF '. The value of ' $x$ ' is

An alternating voltage $\mathrm{V}=100 \sqrt{2} \sin (50 \mathrm{t})$ is connected to $2 \mu \mathrm{~F}$ capacitor through a.c. ammeter. The reading of the ammeter is

An inductor of 0.5 mH , capacitor of $20 \mu \mathrm{~F}$ and resistance of $20 \Omega$ are connected in series with a 220 V a.c. source. If the current is in phase with e.m.f., the maximum current in the circuit is $\sqrt{x} A$. The value of $x$ is