A solenoid with an iron core and a bulb are connected to an a.c. source. The bulb is glowing with certain brightness. When the iron core is removed from the solenoid, the brightness of the bulb

increases

The correct answer is Option (1) → increases

When a solenoid has an iron core, its inductance is higher, leading to greater self-induced emf in opposition to the applied AC, which limits current through the bulb. Removing the iron core reduces the inductance, allowing more current to pass through the bulb.

✅ Therefore, the brightness of the bulb increases.