Question

in which topic electromeric effect is present 12class ​

Answer 1

I don't think so but I am looking for something like that

Answer 2

The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be quickly changed by controlling the amount of electric current in the winding. However, unlike a permanent magnet that needs no power, an electromagnet requires a continuous supply of current to maintain the magnetic field.