A solenoid relay shown in Fig. 35.16 is operated from a 110 V d.c.
supply and the 5000-turn coil resistance is 5.5 kΩ. The core diameter
of the relay is 20 mm and the gap length is 1.5 mm, the armature
being stationary. The gap faces may be taken as parallel and the
permeability of the ferromagnetic parts as very high. Estimate:
(a) the gap flux density;