A magnetic field is generated by a current-carrying wire. Verify the existence of this magnetic field with the LaPlace’s Law Demonstrator. A U-shaped magnet is placed between two separate parallel conductors. Then a rod with a disc is placed across the conductors. This creates a complete conducting path. When a current is passed through the parallel conductors, a force acts on the rod with the disc causing it to roll. 8" L x 5" W x 3¾" H.