A permalloy toroid has relative permeability over the range of interest and carries .

PHYSICS · Multi-part · Fermi University Physics · Electricity, Magnetism & Electromagnetism · Magnetic materials · Magnetic materials

The Boundary-Value Problem, Ch Ferromagnetism: the Weiss field, domains, hysteresis and the magnetic circuit

Problem

A permalloy toroid has relative permeability

\mu_r = 5000

over the range of interest and carries

H = 100\,\mathrm{A\,m^{-1}}

. ((a)) Find

B

and the work done per unit volume by the winding's source in raising

H

linearly from zero to this value. ((b)) Its measured loop saturates at

B_s=0.8\,\mathrm{T}

; with

H

brought back to zero

B

0.4\,\mathrm{T}

, and a reversed field of

1\,\mathrm{A\,m^{-1}}

brings

B

to zero. Give the remanence and the coercivity. ((c)) The loop encloses

5\,\mathrm{J\,m^{-3}}

per cycle. For a core of volume

0.001\,\mathrm{m^3}

driven at

400\,\mathrm{Hz}

, find the power dissipated.