Solution to task 417 from Chertov´s for extramural stud

Solution to task 417 from Chertov´s for extramural stud

417. A square contour with a side d = 10 cm, through which a current I = 50 A flows, is freely established in a uniform magnetic field (B = 10 mT). Determine the change ΔП of the potential energy of the contour when turning around the axis lying in the plane of the contour by an angle υ = 180 °.