Question

A solenoid of 600 turns per metre is carrying a current of 4 A . Its core is made of iron with relative permeability of 5000. Calculate the intensity of magnetisation and magnetic field inside the core .
A. `1.2xx10^(7) Am^(-1) and 15T`
B. `2.3 xx 10^(9) Am^(-1) and 13T `
C. `2.7 xx 10^(11) Am^(-1) and 16T `
D. `1.8 xx 10^(6) Am^(-1) and 14 T `

Answer 1

Correct Answer - A
Give , `i=4A, mu_r=5000 , n=600 tunrs , I=? and B=?`
Now , calculate the value of magnetic intensity H using the formula , `H=ni =600m^(-1) xx 4A=2400 Am^(-1)`
Using the relation , `mu_(r)=1+ chi_(m)`, calculate the value of magnetic susceptibility .
`chi_(m)=mu_(r)-1=5000-1 `
`=4999~~5000`
Now , using the value of ` chi_(m)` to calculate the intensity of magnetisation
`I=chi_(m)H=5000 xx 2400 Am^(-1)`
`=1.2xx10^(7)Am^(-1)`
Now calculate the value of magnetic field B inside the core , using the formula ,
`B=muH=mu_(4)mu_(0)H`
`B=mu_(r) mu_(0)H=5000 mu_(0)H=5000 xx(4pi xx 10^(-7)) xx 2400T `
`:. B=15T `