Question

A solenoid of `500turns` per meter is carrying a current of `3A`. Its core is made of iron, which has a relative permeability of `5000`. Determine the magnitudes of magnetic intensity, intensity of magnetization and magnetic field inside the core.

Answer 1

Here, `n = 500` turns/m,
`i = 3A, mu_(r) = 5000`
Magnetic intensity,
`H = n i = 500 m^(-1) xx 3A = 1500 Am^(-1)`
As `mu_(r) = 1 + chi_(m)`
`:. Chi_(m) = mu_(r) - 1 = 5000 - 1 = 4999 ~~ 5000`
Also, `mu_(r) =(mu)/(mu_(0)) = 5000 :. mu = 5000 mu_(0)`
Intensity of magnetisation,
`I = chi_(m) H = 5000 xx 1500 = 7.5 xx 10^(6) Am^(-1)`
Magnetic field inside the core,
`B = mu H = 5000 mu_(0)H`
`= 5000 (4pi xx 10^(-7)) xx 1500`
`B = 3 pi = 3 xx (22)/(7) = 9.4T`