When a choke is connected in series with a lamp in dc line, the lamp shines brightly. Insertion of an iron core in the choke does not affect the brightness. What happens in case of ac line?

Explanation

An inductance acts as a simple conductor in a dc, line and reducing its self-inductance by introducing an iron case, has no effect on the brightness of the lamp. In ac line the presence of inductances results in a drop a voltage , So the brightness of the lamp decreases. Introduction of the iron core further reduces the brightness of the lamp.