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davidcowling
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Homework Statement
A cast steel magnet has an air gap of length 1mm and an iron path of 30cm. Find the magneto motive force (MMF) necessary to produce a flux density of 1Wb/m^2. The relative permeability of cast steel is 900. Neglect any leakage or fringing effects
Homework Equations
I think these are relevant
Flux density B = mu H
Magnetic field strength H = (NI)/L
Permeance Mu = Mu0 MuR where Mu0 = 4pi *10^-7 and MuR is the relative permeability
MMF = NI
The Attempt at a Solution
i first equated flux density and magnetic field strength together to make
B = 1 = Mu * (NI)/L
i worked Mu out to be approx 1.131*10^-3
Then substituted L as 0.3metres.
this then worked out to be
NI = 0.3 * (1.131*10^-3)
NI is then 3.39*10^-4. Which is the MMF.
Is this correct? Do i have to use the air gap of 1mm for anything?
Your help is appreciated.