A pair of precision coils and 400 turns of wire are wound on former of about 150 mm diameter. The coil is comprised of a support rod, which fits on the holders of the track system supplied, which enables them to be aligned on a common axis for measurements and 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.