The space inside a toroid is filled with tungsten whose susceptibility is `6.8xx10^(-5)` . The percentage increase in the magnetic field will be

Options

A. `2.8 xx10^(-3)`
B. `6.8xx10^(-3)`
C. `4.8 xx 10^(-3)`
D. `5.8xx10^(-3)`

Answer

D

Explanation

Here,l=20 cm,`r=(1)/(2)` cm,n=600,`mu_(r)`=1000,
i=0.5A,I=?
As, `1+x_(m)=pi_(r)`
`x_(m)=pi_(r)-1`ltbrge1000-1=999
H=n i
`=600 xx0.5 =300`
`I+x_(m)H`
`=999xx300=2.997xx10^(5)A//m`