Question

An electromagnet is made of a high permeability ferromagnetic core and a coil. The coil current1A. The electromagnet is just above a fixed ferromagnetic bar. The structural dimensions are length L = 102 cm, cross section area A 4 cm2, and gap g 1cm. The relative permeability values are rc rb 10,000 in the core and bar, respectively, and prg 1 and gap. Ignore leaks and fringe effect. Determine the following: 1. Name of the course the recruiter was referring to. 2. Reluctance of the ferromagnetic material (core and bar) 3. Reluctance of the gap (both sides). 4. EMF 5. Magnetic flux. 6. Sense of the magnetic flux density. 7. Magnetic field intensity in the gap. 8. Total energy stored in the gap. 9. If the bar is set lose, force with which the electromagnet pulls the bar up. 10. Inductance of the structure after the gap disappears BL Ignore BL and BF (leaks)

Answer 1

Given data: - coil current I. M Length (L) 102 cm cross section Area 4cm^2 gap(g) = 1cm Relative permeability mu_r c, mu_r b = 10,000[in core and by] mu_reg = 1[gap] In gore leaks and triangle effect Part A: - name of the course the recruiter was referring to the given circuit system is In given circuit we can observed magnetic flux, field effect Part B: - Reluctance of the Ferro magnetic material in (core and bar) we know that Reluctance = l/mu_0 mu_r n from given data we can substitute the values of A, l, mu_0, mu_r therefore Required Reluctance = l/mu_0mu_rA length (l) = 102 cm (A) area = 4cm^2 = 4 times 10^-4 consider L = 1M mu_r c, mu_r b = 10,000 & mu_r g = 1 Required Reluctance = 1/1 times 10,000 4 times 10^-4 = 1/4 therefore Bar and core reluctance -0.25 r t/