This force names the dual Yang–Mills theory with strong coupling in Montonen-Olive duality. A gravitational analog of this force is often used to explain the frame-dragging caused by rotating objects. The components of this force are the spacelike components of the Faraday tensor. (15[1])What appears to be this force in the observer frame can be derived as a consequence of length contraction of a (-5[1])(*) charge density in a moving particle's rest frame, which is why this force is unified with a counterpart in special relativity. This force can do no work, (10[1]-5[1])since the direction of this force on a particle is always perpendicular to its motion and equals “q v cross B.” (-5[1])For 10 points, moving charges give rise to what force that is combined with electricity in Maxwell’s equations? ■END■ (10[2]0[1])