The electromagnet of Figure P13.28 has reluctance given by ℛ(x) = 7 × 108(0.002 + x) H-1,...

The electromagnet of Figure P13.28 has reluctance given by ℛ(x) = 7 × 108(0.002 + x) H-1, where x is the length of the variable gap in meters. The coil has 980 turns and 30-Ω resistance. For an applied voltage of 120 V DC, find

a. The energy stored in the magnetic field for x = 0.005 m.

b. The magnetic force for x = 0.005 m.

Figure P13.28