  Generally it is accepted that electric field E in type II superconductors is
created by the vortex motion, so that it is proportional to the vortex velocity
v_L. This assertion is based on the Josephson relation E = - v_L x B, which was
derived and is valid if no transport current is present. We present arguments
showing that if transport current is present, static electric field is
proportional to the relative velocity of vortices in respect to the velocity of
superconducting fluid v_s, so that in this case generalised Josephson relation
E = v_s - v_L x B is valid.
