A sample of cast iron exhibits a magnetic field B = 0.5 T , when intensity of magnetising field (H) is `10""(A)/(m)`.
(i) Find permeability of iron .
(ii) What would be the field in air for this value of H ?

Explanation

(i) `mu = (B)/(H)`
= `(0.5)/(10)`
`= (5)/(100)`
`= (1)/(200)`
`= (1)/(20)`
`= 0.05 T""(m)/(A)`
(ii) `B_(0) = mu_(0) H`
`= 4 pi xx 10^(-7) xx 10""(A)/(m)`
`= 4pi xx 10^(-6) T`