Consider a compass placed near a current-carrying conductor. The needle experiences a force and is aligned tangentially to a circle around the conductor. Thus, concentric loops of magnetic fields are formed around the conductor. The direction of the magnetic field generated by the conductor can be determined by the right-hand rule: the thumb points in the direction of the current and the wrapped fingers provide the direction. If the magnetic field moves outward from the plane, it is represented by a dot; if moving toward the plane, it is represented by a cross. Consider an infinitesimal section of the current-carrying conductor in a uniform magnetic field. If n is the number density of free charges, then the number of charge carriers in the section can be determined. Recalling the drift velocity equation, the magnetic force on a single charge and the total magnetic force in the section can be determined. Assuming the length of the infinitesimal section is in the same direction as the drift velocity, the force on the current-carrying conductor can be determined.