A square frame carrying a current I = 0.90 A is located in the same plane as a long straight wire carrying a current I0 = 5.0 A. The frame side has a length a = 8.0 cm. The axis of the frame passing through the midpoints of opposite sides is parallel to the wire and is separated from it by the distance which is times greater than the side of the frame. Find:
(a) Ampere force acting on the frame;
(b) The mechanical work to be performed in order to turn the frame through 180° about its axis, with the currents maintained constant.