The iambic trimeter derives its name from its essential shape, which is three metrical units (hence trimeter) which are each basically iambic in form. The iambic metron has the following shape (where the x is an anceps, the - is a longum, and the u is a brevis):
Hence, reversing the current running though a wire will have the affect of reversing the direction of the magnetic force at a point some distance away from the wire. The affect that this has on the overall magnetic field depends on the shape of the wire.
The magnetic force on a current-carrying wire is perpendicular to both the wire and the magnetic field with direction given by the right hand rule. If the current is perpendicular to the magnetic field then the force is given by the simple product: Data may be entered in any of the fields.