The experiment was successfully repeated with a 24 V/100 W light bulb (so the whole class could see it). A 24 V/100 W light bulb can be purchased in any wholesale shop. We used a coil 11 cm in diameter (a plumber’s pipe can be used) made of four turns of insulated conductor of 1 mm2 size. This coil is connected to the bulb socket (figure 3).