1. Recall if F is the curl of another vector field, then ∇ · F = 0 everywhere. In this problem, you will investigate whether or not
F(x,y,z) = x/(x^2 + y^2 + z^2)^{3/2} i + y/(x^2 + y^2 + z^2)^{3/2} j + z/(x^2 + y^2 + z^2)^{3/2} k
is the curl of another vector field.
(a) Compute the divergence of F.
(b) Let S1 and S2 be the upper and lower halves of the unit sphere, both endowed with upward pointing normal vectors. Argue that if F = curl G for some continuously differentiable vector field G, then flux of F across S1 and the flux of F across S2 are equal.
(c) With S1 and S2 as above, compute the integrals
∬_{S1} (F · n) dσ and ∬_{S2} (F · n) dσ
directly. Is F the curl of another vector field or not?