Let the solenoid of Problem 12.4.4 carry an alternating current of 10 A (rms) at 60 Hz instead of the direct current.
(a) Find an expression for the instantaneous force.
(b) For the numerical values of N, g, a, b, and l given in Problem 12.4.4(b) compute the average force. Compare it to that of
Problem 12.4.4(b).
Problem 12.4.4
A solenoid of cylindrical geometry is shown in Figure P12.4.4.
(a) If the exciting coil carries a steady direct current I, derive an expression for the force on the plunger.
(b) For the numerical values I = 10 A,N = 500 turns, g = 5 mm, a = 20 mm, b = 2 mm, and l = 40 mm, find the magnitude of the force. Assume infinite permeability of the core and neglect leakage.
