An iron-cored $L$ and a bulb $B$ are connected in series to the ac mains in Fig.10.61. The bulb glows with some brightness.

How will the glow of the bulb change if an iron rod is inserted in the coil. Give reasons in support of your answer.

Sketch a graph to show how the reactance of

a capacitor varies as a function of frequency.

Sketch a graph to show how the reactance of an inductor varies as a function of frequency.

Write the expression for frequency of an ideal $LC$ circuit. In an actual circuit, why do the oscillations ultimately die away ?

A reactive element, in an ac circuit, causes the current flowing

to lead in phase by $\frac{\pi }{2},$ with respect to the applied voltage. Identify the element. 

A reactive element, in an ac circuit, causes the current flowing lag in phase by $\frac{\pi }{2}$ with respect to the applied voltage. Identify the element.