A permanent magnet

Problem statement

Consider a permanent magnet with soft iron pole pieces containing an air gap. In the pole pieces and air gap we shall assume that B and H are linearly related through appropiate permeablities.

Extracted from the Part 1A Electromagnetics Handout 3 - Magnetic Materials.

Objective : to find the magnetic field strength B.
Principles : Ampere's Law and flux conservation.

Method of analysis :	1)	Application of Ampere's Law and flux conservation. 
			2)	Interpolate from a magnetisation curve.

Sketch :

Maths :

Matlab(R) solution
Solution variables
Input variables



Mean length of magnet, lm (metres)		
Length of air gap, lg (metres)			
Cross-sec. area of magnet, am (metres)		
Cross-sec. area of air gap, ag (Amperes)	
Field intensity Hm for this magnet		



For B=-b*(H for the magnetic material)

Output variables



Magnetic Flux Density Bm