Question

What is the formula of the specific permeance?

(a) specific permeance = permeability in air * ∫small change in width + length

(b) specific permeance = permeability in air * ∫small change in width/length

(c) specific permeance = permeability in air * ∫small change in width * length

(d) specific permeance = 1/permeability in air * ∫small change in width * length

The question was posed to me in an online quiz.

This key question is from Specific Permeance & Calculation of Magnetizing Current in portion Principles of Magnetic Circuit Design of Design of Electrical Machines

Answer 1

The correct answer is (b) specific permeance = permeability in air * ∫small change in width/length

For explanation I would say: The permeability in air, small change in width and length is calculated first. On substitution the specific permeance is calculated.