A circular wire loop of radius 30 cm carries a current of 3.5 A. Find the magnetic field at a point on its axis 40 cm away from the centre.

Explanation

Radius `(r )=30 cm =30 xx10^(-2)m`
Current `(i) =3.5A`
`x=40 cm =40 xx 10^(-2)m`
`B=(mu_(0) N i r^(2))/(2(R^(2)+x^(2))^(3//2))`
`B=(4pixx10^(-7)xx1xx3.5xx(30xx10^(-2))^(2))/(2[(30xx10^(-2))^(2)+(40xx10^(-2))^(2)]^(3//2))`
`=(4xx3.14xx3.5xx9xx10^(-9))/(2xx10^(-6)[900+1600]^(3//2))`
`=(4xx3.14xx3.5xx9xx10^(-9))/(2xx10^(-3)[125])`
`=(4xx3.14xx3.5xx9xx10^(-9))/(250)`
`B=1.582xx10^(-6) T.`