The magnetic field `B` due to a current carrying circular loop of radius `12cm` at its centre is `0.5xx10^-4T`. Find the magnetic field due to this loop at a point on the axis at a distance of `5.0cm` from the centre.

Explanation

Magnetic field at the centre of a circular loop is
`B_1=(mu_0i)/(2R)`
and that at an axial point, `B_2=(mu_0iR^2)/(2(R^2+x^2)^(3//2)`
Thus, `B_2/B_1=R^3/((R^2+x^2)^(3//2)`
or `B_2=B_1[R^3/((R^2+x^2)^(3//2))]`
Substituting the values we have
`B_2=(0.5xx10^-4)[((12)^3)/((144+25)^(3//2))]`
`=3.9xx10^-5T`