A solenoid , of insulated wire, is wound on a core with relative permeability 400. If the number of turns per metre is 1000 and the solenoid carries a current of 2A, calculate H, B and the magnetisation M.

Explanation

Given , `mu_(r) = 400, I = 2A, n = 1000`
`H = nI = 1000 xx 2 = 2 xx 10^(3)A//m`
`B = mu_(r).mu_(0)H = 400 xx 4pi xx 10^(-7) xx 2 xx 10^(3) = 1.0 T`
Magnetisation `M = (mu_(r) -1)H = (400 - 1)H = 399 xx 2 xx 10^(3)`
`:. M ~= 8 xx 10^(5) A//m`