A light bulb and an air core inductor are connected in series to an a.c. source through a switch. The switch is closed and after sometime, an iron rod is inserted into the interior of the inductor. The light bulb

glows with less brightness

The correct answer is Option (1) → glows with less brightness

When the iron rod is inserted into the air core inductor, the induction increases, leading to an increase in total impedance of circuit.

This causes a decrease in the current through the light bulb, resulting in dimmer light.