A ring
made
up of equal semicircular section
of cast Iron and cast steel with two air gaps
of o-imm and 0.25mm respectively has a cross
soctional area of 400 cm and a mean diameter
of 5m. The ring is uniformly wound with a coil
of 1200 furns. if the relative permeability
of cast iron and cast steel are 2800 and
900 respectively, determine the current
required to produce
a flux of lomwb in​