Page 496 - Basic Electrical Engineering

The various quantities associated with magnetic circuits are stated as
follows.

Magneto motive force (MMF) = Ampere turns = N I

Magnetic field strength

Flux density (B) = Flux per unit area =

Permeability

μ = μ μ r
o

Permeability of free space (air),

μ = 4p × 10 −7
o

Relative permeability (μ ) = The number of times the material is more
r
permeable than air.

Flux density,

B = μH

Flux,

Reluctance,