An inductor L of inductance XL is connected in series with a bulb B and an ac source. How would brightness of the bulb change when (i) number of turn in the inductor is reduced, (ii) an iron rod is inserted in the inductor and (iii) a capacitor of reactance = is inserted in series in the circuit. Justify your answer in each case.

(i) When the number of turns in the inductor is reduced, its reactance X_L decreases. The current in the circuit increases andhence brightness of the bulb increases.

(ii) When an iron rod is inserted in the inductor, the self-inductance increases. Consequently, the inductive reactance X_L = ωL increases. This decreases the current in the circuit and the bulb glows dimmer.

(iii) With capacitor of reactance X_C=X_L, the impedance becomes minimum, the current in circuit becomes maximum. Hence the bulb glows with maximum brightness.