A $12\,\Omega $ resistor and a $0.21\, H$ inductor are connected in series to an $ac$ source operating at $20 \,volts$, $50\,cycle/second$. The phase angle between the current and the source voltage is…..$^o$

A coil has an inductance of $0.7\,henry$ and is joined in series with a resistance of $220\,\Omega $. When the alternating $emf$ of $220\,V$ at $50\,Hz$ is applied to it then the phase through which current lags behind the applied $emf$ and the wattless component of current in the circuit will be respectively

A series $R-C$ circuit is connected to an alternating voltage source. Consider two situations 

$(a)$ When capacitor is air filled.

$(b)$ When capacitor is mica filled.

Current through resistor is $i$ and voltage across capacitor is $V$ then

The rms value of conduction current in a parallel plate capacitor is $6.9\,\mu\,A$. The capacity of this capacitor, if it is connected to $230 V$ ac supply with an angular frequency of $600\,rad / s$, will be $….\,pF$

A light bulb and an open coil inductor are connected to an ac source through a key as shown in Figure

The switch is closed and after sometime, an iron rod is inserted into the interior of the inductor. The glow of the light bulb $(a)$ increases; $(b)$ decreases; $(c)$ is unchanged, as the iron rod is inserted. Give your answer with reasons