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Magnetism and Electromagnetism - Engineering

Q1:

What is the reluctance of a material that has a length of 0.07 m, a cross-sectional area of 0.014 m2, and a permeability of 4,500 Wb/At × m?

A 1111 At/Wb

B 111 At/Wb

C 11 At/Wb

D 1 At/Wb

ANS:A - 1111 At/Wb

Reluctance = length/Uo * Ur * Area.

Given:
Permeability (U) = 4500u Wb/Atxm.
Find Ur (relative permeability):
Ur=Permeability (U) /Free Space Permeability (Uo).

Ur =4500×10^-6 / 4pix10^-7 = 3580.98.
Reluctance = 0.07 / (4pix10^-7) (3580.98) (0.014).
Reluctance = 1111.11 At/Wb.