A long, cylindrical iron core of cross-sectional area `5.00 cm^2` is inserted into a long solenoid having 2000 turns `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=2000m^(-1)xx2A=4000A//m`
Also `B=mu_(0)(H+I)` or,
`I=B/(mu_(0))-H=(1.57T)/(4pixx10^(-7)T-m//A)-4000A/m`
`=(1.25xx10^(6)-4000)A//m=1.25xx10^(6)A//m`
Note again that the magnetization I > > H for iron core. The pole strength developed at the ends is
`m=IA=(1.25xx10^(6)A//m)xx(5xx10^(-4)m^(2))=625A-m`