Circuit boards for current balance set of 3

For demonstrating the force (Lorentz force) of a magnetic field acting on a current-carrying conductor

Set consisting of:
1 Circuit board with 1 turn, 30 cm effective width
1 Circuit board with 2 turns, 30 cm effective width
1 Circuit board with 1 turn, 60 cm effective width
Connection by means of two 4-mm plugs in each case