Question

In a Electromagnetic induction, the copper wire is wrapped on core iron then why doesn't the core iron gets red hot ?

Answer 1

In electromagnetic induction the iron core is not connected to the circuit, so, the little heat developed in the iron core is not due to the ohmic resistance of the core. The core actually gets heated due to the eddy current induced in it due to the change in magnetic field when an AC is passed through the coil.

If we consider a solenoid with a single layer of coil and DC is passed through it we get a constant magnetic field inside the coil given by B = µ₀ nI. Thus, in this case there is no change in magnetic field and hence no heat generated.