This set of 3 plastic liquid-filled devices is used to demonstrate the magnetic field of a current carrying wire in different configurations. This set requires a 12-18 Volt DC power supply. When current is introduced to the wire, the iron filings floating in the viscous liquid will demonstrate the lines of force when moved over the magnetic field. The first demo shows what happens when a flat plane is pierced by a wire carrying a current. The second demo shows what happens when a current carrying loop pierces a plane. The third demonstrates what happens when a current carrying solenoid pierces a plane. Click on the product photos above to enlarge. We introduced current to this set prior to taking the product photos.