​A device ‘X’ is connected to an ac source V = V0 sin wt. The variation of
voltage, current and power in one cycle is shown in the following graph :


(a) Identify the device ‘X’.
(b) Which of the curves A, B and C represent the voltage, current and
the power consumed in the circuit ? Justify your answer.
(c) How does its impedance vary with frequency of the ac source ?
Show graphically.
(d) Obtain an expression for the current in the circuit and its phase
relation with ac voltage.