For studying electromagnetic induction, ferromagnetizm and principles of a transformer. Consists of two coils wound with enamelled copper wire over heavy plastic spools ï¬tting one within the other. The inner primary coil has 1250 turns of heavy wire and the outer, acting as secondary coil with 250 turns of ï¬ne wires. Square supports of thick insulating material are used as vertical or horizontal mount. Both coils are equipped with binding posts and a soft iron core for induction studies.