Solving a problem in physics section 39 paragraph 18 e

18. Direct infinite current I1 = 5A and a rectangular frame with a current I2 = 3A in the same plane so that the side of the frame l = 1 m parallel to the direct current and is separated from it by a distance r = 0,1 b, where b - the length of the other side of the frame. Determine what kind of work you need to make in order to rotate the frame at an angle α = 90 ° relative to the axis OO1, parallel direct current passing through the middle of the opposite sides of the frame b.