[x+1]^2+y^2+z^2=0.2^2

[x-1]^2+y^2+z^2=0.2^2

V=1/([x-1]^2+y^2+z^2)*vector(x-1,y,z)-(1/([x+1]^2+y^2+z^2)*vector(x+1,y,z))

vector(x,y,z)=V,1<abs(V)<2,radius=0.02

function(optotal(t),vector(x,y,z))=V,[x-1]^2+y^2+z^2=0.2^2,radius=0.01

vector(prime(x),prime(y),prime(z))=vector(x+0.3*sin([pi/2*[x-n]]),y,z)

Graph of the formula