A circular ring has a mean diameter of 20 cm and a acrosssectional area of 30 cm. It is wound width a coil of 1200 turns.The ring contains an air gap 1.0 mm long. If the iron has apermeability of 200, what current should be in the coil to producea flux 1.5 x 10^5 Maxwell’s?

a. 1.37 A
b. 11.37 A
c. 13.7 A
d. 1.73 A