  We show that the elastic charge of colloids in a nematic liquid crystal can
be generated by the vector of external torque. The torque components play the
role of two component charge (dyad) and give rise to the Coulomb-like
potential, while their conservation law plays the role similar to that of
Gauss' theorem in the electrostatics. The theory is applied to the
colloid-surface interaction. A wall with homeotropic or planar director is
shown to induce a repulsive 1/r^4 force on the elastic dipole. The external
torque, however, induces the elastic charge in this colloid and triggers
switching to the 1/r^2 repulsion.
