P. 4323. The wire shown in the figure contains a U-shaped part, and is placed to the metal stands such that it can turn easily. Each part of the U-shaped part has a length of =10 cm, and a mass of m=0.15 g.The wire is raised to horizontal position, and a long straight wire, which is parallel to the middle part of the U, is placed below it at a distance of h=2 mm. The two wires are connected in series to a current source. What should the current in the wire be, in order to keep the displaced U-shaped part in the horizontal when it is released?
Solution (in Hungarian)