In Problem 12.4.1 neglect the saturation of the core, leakage, and fringing. Neglect also the reluctance of the ferromagnetic circuit. Assuming that the cross-sectional area of the center leg is twice the area of the outer legs, obtain expressions for the inductance of the coil and the electromagnetic force on the plunger.
Problem 12.4.1
Consider the electromagnetic plunger shown in Figure P12.4.1. The λ-i relationship for the normal working range is experimentally found to be λ = K i2/3/(x +t), where K is a constant. Determine the electromagnetic force on the plunger by the application of Equations (12.4.19) and (12.4.20). Interpret the significance of the sign that you obtain in the force expression.
