Consider a circular loop of radius R that is centered at the origin and lies in a plane with a normal in the direction given by polar angles θ and φ. A current I flows in the loop in an anti-clockwise sense with respect to the normal. The loop is subjected to an external field B = B₀[(1 - 3y)x + (1 + 3x)y].
Find the total force on the loop. Hint: Note that the normal vector is given in spherical polar coordinates (r, θ, φ) so that the current element can be expressed in terms of θ and φ. Also make use of the cross product (z x r) and the identity for the triple vector product.