Question

A flux density of 1.2Wb/m^2 is required in the 1 mm air gap of an electromagnet having an iron path of length 1.5 m. Calculate the mmf required. Given, relative permeability of iron is 1600. Neglect leakage. ​

Answer 1

Answer:

The mmf required is $1.125$×$10^{-3}$ A

Explanation:

The Magnetomotive force (mmf) is given by the formula below

$F_{M} = Hl$

where $F_{M}$ is the Magnetomotive force (mmf)

$H$ is the Magnetic field strength

$l$ is the magnetic length

The magnetic permeability μ is given by

μ = $B / H$

Where $B$ is the Magnetic flux density

and $H$ is the Magnetic field strength

From the question,

$B$ = 1.2Wb/m^2

μ = 1600m

From μ = $B / H$

∴$H = B/$μ

$H = 1.2 / 1600$

$H = 7.5$ × $10^{-4}$A/m

Now, for the Magnetomotive force (mmf)

$F_{M} = Hl$

From the question

$l$ = 1.5 m

∴ $F_{M} = 7.5$×$10^{-4}$ × $1.5$

$F_{M} = 1.125$×$10^{-3} A$

Hence, The mmf required is $1.125$×$10^{-3}$ A