A ring of mean radius `15cm` has `3500` turns of wire wound on a ferromagnetic core of relative permeability `800`. What is the magnetic field in the core for a magnetising current of `2*4A`?

Explanation

Here, `r=15cm=15xx10^-2m, N=3500`
`mu_r=800`, `B=?` `I=2*4A`
Number of turns per unit length
`n=(N)/(2pir)=(3500)/(2pi(15xx10^-2))`
`B=(mu_0mu_r)nI`
`=4pixx10^-7xx800xx(3500xx2.4)/(2pi(15xx10^-2))`
`B=8*96T`