(1) (2i RB) upward
The directions of forces F1 , F2 and F3 is marked as per the Fleming’s Left hand rule.
Since force F1 and F2 are acting in opposite directions and are equal in magnitude, they cancel each other’s effect.
Hence the total force on the given loop is due to the semi circular portion,
which is equal to
= 2iRB acting upward on the given loop.