A long, cylindrical iron core of cross-sectional area `5.00 cm^2` is inserted into a long solenoid having 2000 tunres `m^(-1)` and carrying a current `2.00 A`. The magnetic field inside the core is found to be `1.57 T`. Neglecting the end effects, find the magnetization `I` of the core and the pole strength developed.

Explanation

The magnetic intensity `H` inside the solenoid is `H = ni = 2000 m^(-1) xx 2 A = 4000 A m^(-1)`.
Aslo `B = mu_0 (H+I)`
or, `I = B/(mu_0) = H`
`= (1.57 T)/(4pi xx 10^(-7) Tm A^(-1)`.
`= (1.25 xx 10^6 - 4000) A m^(-1) = 1.25 xx 10^6 A m^(-1)`.
Note gain that the magnetization `I gt gt H` for iron core. The pole strentgh developed at the end is
`m = IA`.
`= (1.25 xx 10^6 A m^(-1)) xx (5 xx 10^(-1) xx (5 xx 10^(-4) m^2) = 625 A m`