The core is made of cast steel. Find the MMF required to get an air gap flux of 60,000 lines. The cross sectional area of the center section and air gaps is 4 in^2. The remaining sections have a cross sectional of 6 in^2. The air gaps are both 0.06 in.The lengths are L1= 7 in across and L2 = 4 in. down.The answer is 1900A-T.