= Electrophoretic motion of a sphere with a thin double layer. Determine the translational velocity of a sphere placed in an electric field E; when the double layer around the sphere is small compared with the radius of the sphere so that the flow outside the double layer may be approximated by a tangential slip velocity given by wit = a Et where the superscript t denotes tangential component at the surface of the sphere and a = 60]/kT and s the difference between the velocity of the fluid and a - that of the surface of the sphere. (Hint: This problem is very similar to the Problem 1, the main difference being that you are given a condition for the tangential component of the velocity instead of the tangential component of the stress. The net force on the sphere is zero and therefore the velocity must decay faster than 1/r and the electric field potential satisfies Laplace equation with the boundary condition that the normal component of the electric field must equal zero at the surface of the particle.)