In a series $LCR$ circuit at resonance,the phase difference between voltage and current is

What will be the reading of the voltmeter in the given circuit (in $V$)?

An inductor of $0.5 \text{ mH}$, a capacitor of $20 \text{ } \mu\text{F}$ and resistance $20 \text{ } \Omega$ are connected in series with a $220 \text{ V}$ ac source. If the current is in phase with the emf, the amplitude of current of the circuit is $[x]^{1/2} \text{ A}$. The value of $x$ is

$A$ series resonant circuit consists of an inductor '$L$' of negligible resistance and a capacitor '$C$' which produces a resonant frequency '$f$'. If '$L$' is changed to $3L$ and '$C$' is changed to $6C$,the new resonant frequency will become:

At resonance,the value of current in a series $L-C-R$ circuit is: (Symbols have their usual meanings.)

The current in a series $LCR$ circuit will be maximum when $\omega$ is