The magnetic system of Fig. 3.35 has a square cross section 30 x 30 mm. When the two sections of the core are fitted together, air gaps, each of length x = 1.0 mm, separate them. The coil has 250 turns and a resistance c gure 3.35 Magnetic system for Problem 3.20. X of 7.5 Q. The magnetic field intensity required by the core material is neg- ligible. (a) If a constant voltage source of 40 V is connected to the coil terminals, what will be the total force holding the two sections together? (b) If a sinusoidal voltage of 100 V at 60 Hz is connected to the coil ter- minals, what is the average force holding the two sections together? (c) The effect of flux fringing can be allowed for by assuming that the air- gap flux density is uniform over a gap with dimensions (30 + x) in each direction for a gap length x. Repeat (b) and (c) including this effect.