The impedance of a circuit,when a resistance $R$ and an inductor of inductance $L$ are connected in series in an $AC$ circuit of frequency $f$ is

$A$ $220\, V$,$50\, Hz$ $ac$ source is connected to an inductance of $0.2\, H$ and a resistance of $20\, \Omega$ in series. What is the current in the circuit (in $, A$)?

An inductor and a resistor are connected in series to an ac source of variable frequency. When the frequency of the applied ac is $50 \ Hz$,the power factor of the circuit is $\frac{\sqrt{3}}{2}$. If the frequency of the ac is increased by $200 \%$,the power factor of the circuit is . . . . . . .

For a series $LCR$ circuit,which one of the following is a $CORRECT$ statement?

If a dielectric slab is inserted in the capacitor of the given $RC$ circuit,then the brightness of the bulb will:

An electric lamp connected in series with a capacitor and an $A.C.$ source is glowing with a certain brightness. On increasing the value of capacitance,the brightness of the lamp