A pair of precision coils with 4mm terminals. 400 turns of copper wire are wound on a former of about 150mm diameter. The coil is comprised of a support rod, which fits on the holders of the track system supplied, enabling them to be aligned on a common axis for measurements and the study of the magnetic fields. Normally used in pairs, each coil has 4 mm terminals and their distance apart is adjusted over the track supplied. The maximum current in the coil is 1A to avoid overheating. Direction of current is marked on each coil. 

• The minimum & maximum distance the coils can be apart is 44.5mm to 305mm (1.75" to 12"). 
• The overall dimensions are (H)165mm x (L)280mm x (W)165mm (6.5" height, 11" length, 6.5" width).