Hi, I'm writing a small simulator where two objects apply force on each other inversely proportional to square of distance between them. ( like gravty ) in terms of gravity, I think this is the only force that I have to take into consideration. but I'm confused about electrical and magnetic force. When the point charges are not moving, the force between them is only electrical ( F = k*q1*q2/d^2 ) but as they start to move, and because a moving charge is "current", one will start to generate a magnetic field and the other will be effected from this field. ( correct ? biot-savart ) in addition to electrical field. the particles may have some non-zero initial velocity and the particles may not have aimed towards each other. Generally: how do I calculate the magnetic field of a moving point charge? ( and finally apply it to the other by F = qVxB where B is the magnetic field generated by other particle ) in addition to attractive electrical force, can opposite charged particles apply "repulsive" magnetic force to each other? Can someone clarify this to me? Thanks. PS: how do i calculate the "current" related to the motion of a charged particle? does accelerated motion or constant velocity motion result in different currents? in general: are electrons moving at constant velocity within a wire or are they accelerated from one pole of battery to the other?