The effective resistance of an iron-cored choke working on ordinary supply frequency is more than its true resistance because of

Solution(By Examveda Team)

Imagine an iron-cored choke as a coil of wire wrapped around an iron core. When AC electricity flows through it, two main things happen:

1. True Resistance: The wire itself has some resistance, this is what we call the "true resistance". It's like friction in a pipe that slows down water flow.

2. Iron Losses: The changing magnetic field in the iron core causes energy to be lost as heat. This is called iron loss, and it's like energy leaking out of the pipe.

This iron loss acts like extra resistance, making it seem like the coil has a higher resistance than it actually does. This is called effective resistance. It's the total resistance considering both the wire's resistance and the energy lost in the core.

Therefore, the effective resistance is higher than the true resistance because of the iron loss in the core. The other options (skin effect, temperature increase, and capacitive effect) also contribute to losses, but the primary reason in this specific scenario involving an iron-cored choke on an ordinary supply frequency is the iron loss.