What is the inductance of an air-cored coil with 1000 turns, crosssectional area 400 mm2 and length 150 mm? A 100 turn coil is wound on an iron rod of diameter 10 mm. If the rod and coil have a length...

What is the inductance of an air-cored coil with 1000 turns, crosssectional area 400 mm2 and length 150 mm?

A 100 turn coil is wound on an iron rod of diameter 10 mm. If the rod and coil have a length of 40 mm and the relative permeability of the iron is constant at 400, what is its inductance?