Why we use k here in place of n as marked by red pen in picture....

ancle.com Physics (USP (ydx+zdy+ xdz) = oydx, sin ce on C, z = 0 and dz = 0 sintdt=sin tdt dt (1-cos 2t) dt =- Sin 2t -2T 2 Now let us evaluate curl Fen dS we have curlF ik F Ox oy Oz Z x If S, is the plane region bounded by the circle C, then by an application of divergence theorem, we have curl F.n dS = |, curl Fk dS J. (H-1-k)-k,dS- J], (-1)ds =- ds--S But S,= area of a circle of radius 1 r(1)? = T. curl F.n dS =-T =- 3.14 9.23