Question

Why do magnetic field lines prefer to pass through iron than air?

Answer 1

Answer:

Higher permeability

Explanation:

Permeability of ferromagnetic materials are high as compered to air. Magnetic lines of forces are always prefer to pass through higher permeability materials. Iron is best example for ferromagnetic materials. Thus  magnetic field lines prefer to pass through iron than air.

Answer 2

Answer:

Because iron allow current to pass through it easily.